The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructur...The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.展开更多
Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with ex...Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with excellent performance.Over the past decade,significant progress has been achieved in deeply understanding the SSP process,the microstructure and performance of the fabricated components in China.This paper starts with a retrospective overview of some common slurry preparation methods,followed by presenting the performance and the underlying mechanisms of SSP fabricated alloys.Then,the mainstream opinions on the microstructure evolution and rheological flow behavior of semi-solid slurry are discussed.Subsequently,the general situation and some recent examples of industrial applications of SSP are presented.Finally,special attention is paid to the unresolved issues and the future directions in SSP of Al and Mg alloys in China.展开更多
Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and al...Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements,hardness and impact strength of GISS alloys were investigated.Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primaryα(A1)in the alloy to change from coarse dendritic to fine globular structure.The best sample which has fine grains of 51.18μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610℃.The impact strength of the GISS optimized samples((4.67±0.18)J/cm^(2))shows an increase of about 40%with respect to the as-cast sample due to the globular structure and fibrous Si morphology.Moreover,the hardness of the optimized GISS sample((89.34±2.85)HB)increases to(93.84±3.14)HB by modification with the Sr and GISS process.The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.展开更多
EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃...EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃ and destabilisation at 1075℃ plus tempering at 500℃, all followed by air cooling. Electron microscopy revealed that, in the as-cast condition, the primary proeutectic austenite was round in shape while the eutectic M7C3 carbide was found as radiating clusters mixed with directional clusters. Tempering did not change the microstructure significantly when observed by scanning or transmission electron microscopy. Destabilisation followed by air cooling led to a precipitation of secondary M23C6 carbide and a transformation of the primary austenite to martensite. Precipitation behaviour is comparable to that observed in the conventionally cast iron. Tempering after destabilisation resulted in a higher amount of secondary carbide precipitation within the tempered martensite in the eutectic structure. Vickers macrohardness and microhardness in the proeutectic zones were measured. Dry wear properties were tested by using a pin-on-disc method. The maximum hardness and the lowest dry wear rate were obtained from the destabilisation-plus-tempering heat treatment due to the precipitation of secondary carbides within the martensite matrix and a possible reduction in the retained austenite.展开更多
It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and se...It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.展开更多
The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore...The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore the possibility of the semi-solid process in manufacturing Ti-47Al-2Cr-2Nb-0.8 B(at%)alloy.An important result is that,except forming a nondendritic globular structure,the semi-solid process also plays a crucial role in refining large borides for the TiAl alloys with boron.In the current alloy,the long ribbon borides can be successfully converted to fine,equiaxed particles with an average size of 2-5μm.Furthermore,subsequent proper heat treatment is necessary to control and achieve a fine,nearly fully lamellar microstructure.The key microstructure-refinement mechanism is due to the fine borides obtained during semisolid process,which act as the effective nucleation centers for the formation of interdendritic fine y grains,providing the pinning effect on priorα-grain boundaries.These results prove that semi-solid process can be an ideal candidate for the microstructure refinement in TiAl alloys.展开更多
An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were grad...An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.展开更多
The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding u...The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（Al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（Al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.展开更多
The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting indust...The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.展开更多
Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle o...Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.展开更多
The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity de...The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.展开更多
The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequ...The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequently,under the same condition of thixoforming,the microstructure,surface hardness and tensile properties were observed.Afterwards,quantitative analysis was made for the microstructures of the reheated semi-solid of billet and the thixoforming parts.The results show that when the induction reheating power is 90 kW,the average grain size of the semi-solid billet is the minimum,the microstructures of the thixoforming samples also are the finest,and the mechanical properties of the relevant thixoforming samples are the best.Furthermore,after studying on the relationship between the microstructures of the semi-solid billet of aluminum alloy and the mechanical properties of the thixoforming samples,the reverse design of microstructure is primarily achieved.Finally,the effectiveness of the reverse design for semi-solid microstructure is confirmed by an actual automobile part with complex shape.展开更多
Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application...Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application as a function of processing parameters were compared with those of die-cast parts and forged parts. In addition, the locations for the gate during the semi-solid processing were varied to elucidate the distribution of micro-porosities and resulting mechanical properties and the T6 heat tre...展开更多
一、作为哲学的AI for Process(一)郭为的哲学思想1.郭为是谁郭为是谁?他是一位哲学家。顺便说,他同时还领导着神州数码。为什么说郭为是哲学家呢?因为他在著作中谈到高深的哲学,如“数据如水,奔流不息,无界融合”。他引述古希腊哲学家...一、作为哲学的AI for Process(一)郭为的哲学思想1.郭为是谁郭为是谁?他是一位哲学家。顺便说,他同时还领导着神州数码。为什么说郭为是哲学家呢?因为他在著作中谈到高深的哲学,如“数据如水,奔流不息,无界融合”。他引述古希腊哲学家赫拉克利特所说的“万物流转”,又说“你不能两次踏进同一条河流,因为新的水不断地流过你的身旁”,他所表达的意思是“世界上唯一不变的就是变化”。展开更多
Through the innovative integration of semi-solid rheo-casting with extrusion shear process,the short-process fabrication of low-alloyed wrought Mg-2Zn-1Mn alloy is achieved in this study.Uniaxial tensile testing of lo...Through the innovative integration of semi-solid rheo-casting with extrusion shear process,the short-process fabrication of low-alloyed wrought Mg-2Zn-1Mn alloy is achieved in this study.Uniaxial tensile testing of low-temperature extrusion shear specimens(200℃)demonstrates the exceptional strength-ductility synergy,yield strength of 277 MPa,yield strength ratio of 0.95,and elongation of 24%.Microstructural observations reveal the mechanisms underlying its high strength-plasticity synergy at room temperature.This study investigates the effects of different temperature gradients on the microstructure by analyzing experiments conducted at three temperatures:300℃,250℃,and 200◦C.Ultimately,the formation mechanism of the bimodal microstructure obtained at 200℃ is elucidated.The distinctive crystallographic texture oriented at 34°relative to the loading axis direction effectively mitigates stress concentration by inducing the synergistic activation of multiple slip systems.Furthermore,the transition trends of different slip systems and texture evolution during tensile deformation are validated through Visco-Plastic Self-Consistent(VPSC)simulations and corroborated by microstructural analysis.With geometrically necessary dislocation(GND)density(4.28×10^(15)m^(-2))and pyramidal slip activation(~45%).This study has successfully broken through the bottleneck of strength-ductility trade-off in magnesium alloys,providing theoretical support for the development of high-reliability magnesium alloys.展开更多
Agricultural Products Processing and Storage(ISSN 3059-4510,Owner:Hunan Academy of Agricultural Sciences,China.Production and hosting:Springer Nature)is an international,peer-reviewed open access journal with the aim ...Agricultural Products Processing and Storage(ISSN 3059-4510,Owner:Hunan Academy of Agricultural Sciences,China.Production and hosting:Springer Nature)is an international,peer-reviewed open access journal with the aim to offer a platform for the rapid dissemination of signifi cant,novel,and high-impact research in the fi elds of agricultural product processing science,technology,engineering,and nutrition.Additionally,supplemental issues are curated and published to facilitate in-depth discussions on special topics.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
Processes supported by process-aware information systems are subject to continuous and often subtle changes due to evolving operational,organizational,or regulatory factors.These changes,referred to as incremental con...Processes supported by process-aware information systems are subject to continuous and often subtle changes due to evolving operational,organizational,or regulatory factors.These changes,referred to as incremental concept drift,gradually alter the behavior or structure of processes,making their detection and localization a challenging task.Traditional process mining techniques frequently assume process stationarity and are limited in their ability to detect such drift,particularly from a control-flow perspective.The objective of this research is to develop an interpretable and robust framework capable of detecting and localizing incremental concept drift in event logs,with a specific emphasis on the structural evolution of control-flow semantics in processes.We propose DriftXMiner,a control-flow-aware hybrid framework that combines statistical,machine learning,and process model analysis techniques.The approach comprises three key components:(1)Cumulative Drift Scanner that tracks directional statistical deviations to detect early drift signals;(2)a Temporal Clustering and Drift-Aware Forest Ensemble(DAFE)to capture distributional and classification-level changes in process behavior;and(3)Petri net-based process model reconstruction,which enables the precise localization of structural drift using transition deviation metrics and replay fitness scores.Experimental validation on the BPI Challenge 2017 event log demonstrates that DriftXMiner effectively identifies and localizes gradual and incremental process drift over time.The framework achieves a detection accuracy of 92.5%,a localization precision of 90.3%,and an F1-score of 0.91,outperforming competitive baselines such as CUSUM+Histograms and ADWIN+Alpha Miner.Visual analyses further confirm that identified drift points align with transitions in control-flow models and behavioral cluster structures.DriftXMiner offers a novel and interpretable solution for incremental concept drift detection and localization in dynamic,process-aware systems.By integrating statistical signal accumulation,temporal behavior profiling,and structural process mining,the framework enables finegrained drift explanation and supports adaptive process intelligence in evolving environments.Its modular architecture supports extension to streaming data and real-time monitoring contexts.展开更多
The aging process is an inexorable fact throughout our lives and is considered a major factor in develo ping neurological dysfunctions associated with cognitive,emotional,and motor impairments.Aging-associated neurode...The aging process is an inexorable fact throughout our lives and is considered a major factor in develo ping neurological dysfunctions associated with cognitive,emotional,and motor impairments.Aging-associated neurodegenerative diseases are characterized by the progressive loss of neuronal structure and function.展开更多
The complexity of the seismicity pattern for the subduction zone along the oceanic plate triggered the outer rise events and revealed cyclic tectonic deformation conditions along the plate subduction zones.The outer r...The complexity of the seismicity pattern for the subduction zone along the oceanic plate triggered the outer rise events and revealed cyclic tectonic deformation conditions along the plate subduction zones.The outer rise earthquakes have been observed along the Sunda arc,following the estimated rupture area of the 2005 M_(W)8.6 Nias earthquakes.Here,we used kinematic waveform inversion(KIWI)to obtain the source parameters of the 14 May 2021 M_(W)6.6 event off the west coast of northern Sumatra and to define the fault plane that triggered this outer rise event.The KIWI algorithm allows two types of seismic source to be configured:the moment tensor model to describe the type of shear with six moment tensor components and the Eikonal model for the rupture of pure double-couple sources.This method was chosen for its flexibility to be applied for different sources of seismicity and also for the automated full-moment tensor solution with real-time monitoring.We used full waveform traces from 8 broadband seismic stations within 1000 km epicentral distances sourced from the Incorporated Research Institutions for Seismology(IRIS-IDA)and Geofon GFZ seismic record databases.The initial origin time and hypocenter values are obtained from the IRIS-IDA.The synthetic seismograms used in the inversion process are based on the existing regional green function database model and were accessed from the KIWI Tools Green's Function Database.The obtained scalar seismic moment value is 1.18×10^(19)N·m,equivalent to a moment magnitude M_(W)6.6.The source parameters are 140°,44°,and−99°for the strike,dip,and rake values at a centroid depth of 10.2 km,indicating that this event is a normal fault earthquake that occurred in the outer rise area.The outer rise events with normal faults typically occur at the shallow part of the plate,with nodal-plane dips predominantly in the range of 30°-60°on the weak oceanic lithosphere due to hydrothermal alteration.The stress regime around the plate subduction zone varies both temporally and spatially due to the cyclic influences of megathrust earthquakes.Tensional outer rise earthquakes tend to occur after the megathrust events.The relative timing of these events is not known due to the viscous relaxation of the down going slab and poroelastic response in the trench slope region.The occurrence of the 14 May 2021 earthquake shows the seismicity in the outer rise region in the strongly coupled Sunda arc subduction zone due to elastic bending stress within the duration of the seismic cycle.展开更多
文摘The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.
基金financial supports from the Shenzhen Science and Technology Innovation Commission, China (Nos. KQTD20170328154443162, JCYJ20180305123432756)。
文摘Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with excellent performance.Over the past decade,significant progress has been achieved in deeply understanding the SSP process,the microstructure and performance of the fabricated components in China.This paper starts with a retrospective overview of some common slurry preparation methods,followed by presenting the performance and the underlying mechanisms of SSP fabricated alloys.Then,the mainstream opinions on the microstructure evolution and rheological flow behavior of semi-solid slurry are discussed.Subsequently,the general situation and some recent examples of industrial applications of SSP are presented.Finally,special attention is paid to the unresolved issues and the future directions in SSP of Al and Mg alloys in China.
文摘Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements,hardness and impact strength of GISS alloys were investigated.Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primaryα(A1)in the alloy to change from coarse dendritic to fine globular structure.The best sample which has fine grains of 51.18μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610℃.The impact strength of the GISS optimized samples((4.67±0.18)J/cm^(2))shows an increase of about 40%with respect to the as-cast sample due to the globular structure and fibrous Si morphology.Moreover,the hardness of the optimized GISS sample((89.34±2.85)HB)increases to(93.84±3.14)HB by modification with the Sr and GISS process.The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.
文摘EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃ and destabilisation at 1075℃ plus tempering at 500℃, all followed by air cooling. Electron microscopy revealed that, in the as-cast condition, the primary proeutectic austenite was round in shape while the eutectic M7C3 carbide was found as radiating clusters mixed with directional clusters. Tempering did not change the microstructure significantly when observed by scanning or transmission electron microscopy. Destabilisation followed by air cooling led to a precipitation of secondary M23C6 carbide and a transformation of the primary austenite to martensite. Precipitation behaviour is comparable to that observed in the conventionally cast iron. Tempering after destabilisation resulted in a higher amount of secondary carbide precipitation within the tempered martensite in the eutectic structure. Vickers macrohardness and microhardness in the proeutectic zones were measured. Dry wear properties were tested by using a pin-on-disc method. The maximum hardness and the lowest dry wear rate were obtained from the destabilisation-plus-tempering heat treatment due to the precipitation of secondary carbides within the martensite matrix and a possible reduction in the retained austenite.
基金This Work financially supported by the China National Advanced Materials Committee
文摘It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.
基金the National Natural Science Foundation of China(No.51101003)。
文摘The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore the possibility of the semi-solid process in manufacturing Ti-47Al-2Cr-2Nb-0.8 B(at%)alloy.An important result is that,except forming a nondendritic globular structure,the semi-solid process also plays a crucial role in refining large borides for the TiAl alloys with boron.In the current alloy,the long ribbon borides can be successfully converted to fine,equiaxed particles with an average size of 2-5μm.Furthermore,subsequent proper heat treatment is necessary to control and achieve a fine,nearly fully lamellar microstructure.The key microstructure-refinement mechanism is due to the fine borides obtained during semisolid process,which act as the effective nucleation centers for the formation of interdendritic fine y grains,providing the pinning effect on priorα-grain boundaries.These results prove that semi-solid process can be an ideal candidate for the microstructure refinement in TiAl alloys.
文摘An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.
基金the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Rio Tinto Alcan through the NSERC Industrial Research Chair in Metallurgy of Aluminum Transformation at Université du Québec à Chicoutimi
文摘The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（Al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（Al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.
基金supports from Prince of Songkla University (No.AGR530031M)the Royal Golden Jubilee Ph.D program (No.PHD/0173/2550)
文摘The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.
基金supports from several sources including the Thai Research Fund (No. MRG5280215)Prince of Songkla University (No. AGR530031M)the Royal Golden Jubilee Ph.D. Program (No. PHD/0134/2551 and PHD/0173/2550)
文摘Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.
基金the funding from Princeof Songkla University for Ph.D. 50% Scholarship,the Royal Golden Jubilee Ph.D. program (Grant No.PHD/0173/2550)
文摘The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.
文摘The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequently,under the same condition of thixoforming,the microstructure,surface hardness and tensile properties were observed.Afterwards,quantitative analysis was made for the microstructures of the reheated semi-solid of billet and the thixoforming parts.The results show that when the induction reheating power is 90 kW,the average grain size of the semi-solid billet is the minimum,the microstructures of the thixoforming samples also are the finest,and the mechanical properties of the relevant thixoforming samples are the best.Furthermore,after studying on the relationship between the microstructures of the semi-solid billet of aluminum alloy and the mechanical properties of the thixoforming samples,the reverse design of microstructure is primarily achieved.Finally,the effectiveness of the reverse design for semi-solid microstructure is confirmed by an actual automobile part with complex shape.
文摘Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application as a function of processing parameters were compared with those of die-cast parts and forged parts. In addition, the locations for the gate during the semi-solid processing were varied to elucidate the distribution of micro-porosities and resulting mechanical properties and the T6 heat tre...
文摘一、作为哲学的AI for Process(一)郭为的哲学思想1.郭为是谁郭为是谁?他是一位哲学家。顺便说,他同时还领导着神州数码。为什么说郭为是哲学家呢?因为他在著作中谈到高深的哲学,如“数据如水,奔流不息,无界融合”。他引述古希腊哲学家赫拉克利特所说的“万物流转”,又说“你不能两次踏进同一条河流,因为新的水不断地流过你的身旁”,他所表达的意思是“世界上唯一不变的就是变化”。
基金the financial support from Basic Research Projects of Higher Education Institutions of Liaoning Province(Key Research Projects)(No.JYTZD2023108)General Project of Liaoning Provincial Department of Education(Nos.LJKMZ20220462 and JYTMS20231199).
文摘Through the innovative integration of semi-solid rheo-casting with extrusion shear process,the short-process fabrication of low-alloyed wrought Mg-2Zn-1Mn alloy is achieved in this study.Uniaxial tensile testing of low-temperature extrusion shear specimens(200℃)demonstrates the exceptional strength-ductility synergy,yield strength of 277 MPa,yield strength ratio of 0.95,and elongation of 24%.Microstructural observations reveal the mechanisms underlying its high strength-plasticity synergy at room temperature.This study investigates the effects of different temperature gradients on the microstructure by analyzing experiments conducted at three temperatures:300℃,250℃,and 200◦C.Ultimately,the formation mechanism of the bimodal microstructure obtained at 200℃ is elucidated.The distinctive crystallographic texture oriented at 34°relative to the loading axis direction effectively mitigates stress concentration by inducing the synergistic activation of multiple slip systems.Furthermore,the transition trends of different slip systems and texture evolution during tensile deformation are validated through Visco-Plastic Self-Consistent(VPSC)simulations and corroborated by microstructural analysis.With geometrically necessary dislocation(GND)density(4.28×10^(15)m^(-2))and pyramidal slip activation(~45%).This study has successfully broken through the bottleneck of strength-ductility trade-off in magnesium alloys,providing theoretical support for the development of high-reliability magnesium alloys.
文摘Agricultural Products Processing and Storage(ISSN 3059-4510,Owner:Hunan Academy of Agricultural Sciences,China.Production and hosting:Springer Nature)is an international,peer-reviewed open access journal with the aim to offer a platform for the rapid dissemination of signifi cant,novel,and high-impact research in the fi elds of agricultural product processing science,technology,engineering,and nutrition.Additionally,supplemental issues are curated and published to facilitate in-depth discussions on special topics.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
文摘Processes supported by process-aware information systems are subject to continuous and often subtle changes due to evolving operational,organizational,or regulatory factors.These changes,referred to as incremental concept drift,gradually alter the behavior or structure of processes,making their detection and localization a challenging task.Traditional process mining techniques frequently assume process stationarity and are limited in their ability to detect such drift,particularly from a control-flow perspective.The objective of this research is to develop an interpretable and robust framework capable of detecting and localizing incremental concept drift in event logs,with a specific emphasis on the structural evolution of control-flow semantics in processes.We propose DriftXMiner,a control-flow-aware hybrid framework that combines statistical,machine learning,and process model analysis techniques.The approach comprises three key components:(1)Cumulative Drift Scanner that tracks directional statistical deviations to detect early drift signals;(2)a Temporal Clustering and Drift-Aware Forest Ensemble(DAFE)to capture distributional and classification-level changes in process behavior;and(3)Petri net-based process model reconstruction,which enables the precise localization of structural drift using transition deviation metrics and replay fitness scores.Experimental validation on the BPI Challenge 2017 event log demonstrates that DriftXMiner effectively identifies and localizes gradual and incremental process drift over time.The framework achieves a detection accuracy of 92.5%,a localization precision of 90.3%,and an F1-score of 0.91,outperforming competitive baselines such as CUSUM+Histograms and ADWIN+Alpha Miner.Visual analyses further confirm that identified drift points align with transitions in control-flow models and behavioral cluster structures.DriftXMiner offers a novel and interpretable solution for incremental concept drift detection and localization in dynamic,process-aware systems.By integrating statistical signal accumulation,temporal behavior profiling,and structural process mining,the framework enables finegrained drift explanation and supports adaptive process intelligence in evolving environments.Its modular architecture supports extension to streaming data and real-time monitoring contexts.
文摘The aging process is an inexorable fact throughout our lives and is considered a major factor in develo ping neurological dysfunctions associated with cognitive,emotional,and motor impairments.Aging-associated neurodegenerative diseases are characterized by the progressive loss of neuronal structure and function.
基金supported by the National Natural Science Foundation of China(Grant No.42130312)。
文摘The complexity of the seismicity pattern for the subduction zone along the oceanic plate triggered the outer rise events and revealed cyclic tectonic deformation conditions along the plate subduction zones.The outer rise earthquakes have been observed along the Sunda arc,following the estimated rupture area of the 2005 M_(W)8.6 Nias earthquakes.Here,we used kinematic waveform inversion(KIWI)to obtain the source parameters of the 14 May 2021 M_(W)6.6 event off the west coast of northern Sumatra and to define the fault plane that triggered this outer rise event.The KIWI algorithm allows two types of seismic source to be configured:the moment tensor model to describe the type of shear with six moment tensor components and the Eikonal model for the rupture of pure double-couple sources.This method was chosen for its flexibility to be applied for different sources of seismicity and also for the automated full-moment tensor solution with real-time monitoring.We used full waveform traces from 8 broadband seismic stations within 1000 km epicentral distances sourced from the Incorporated Research Institutions for Seismology(IRIS-IDA)and Geofon GFZ seismic record databases.The initial origin time and hypocenter values are obtained from the IRIS-IDA.The synthetic seismograms used in the inversion process are based on the existing regional green function database model and were accessed from the KIWI Tools Green's Function Database.The obtained scalar seismic moment value is 1.18×10^(19)N·m,equivalent to a moment magnitude M_(W)6.6.The source parameters are 140°,44°,and−99°for the strike,dip,and rake values at a centroid depth of 10.2 km,indicating that this event is a normal fault earthquake that occurred in the outer rise area.The outer rise events with normal faults typically occur at the shallow part of the plate,with nodal-plane dips predominantly in the range of 30°-60°on the weak oceanic lithosphere due to hydrothermal alteration.The stress regime around the plate subduction zone varies both temporally and spatially due to the cyclic influences of megathrust earthquakes.Tensional outer rise earthquakes tend to occur after the megathrust events.The relative timing of these events is not known due to the viscous relaxation of the down going slab and poroelastic response in the trench slope region.The occurrence of the 14 May 2021 earthquake shows the seismicity in the outer rise region in the strongly coupled Sunda arc subduction zone due to elastic bending stress within the duration of the seismic cycle.
