Shielded Metal Arc Welding (SMAW) in Ductile Irons (DI) is often required by foundries for practical manufacturing reasons. The mechanical properties of the welded structures are strongly dependent on their HAZ’s wid...Shielded Metal Arc Welding (SMAW) in Ductile Irons (DI) is often required by foundries for practical manufacturing reasons. The mechanical properties of the welded structures are strongly dependent on their HAZ’s width. A model based on the behaviour of the ferritic matrix of high-Si DIs in order to make an approach in measuring their HAZ’s width is developed in this study. A series of thermal treatments on 3.35 and 3.75 wt% Si as-cast DIs and spot SMAWs is applied on these materials. The applied SMAWs are done on non-preheated and preheated samples (150℃ - 300℃). For welding we modify the amperage (100 - 140A). The micro-hardness Vickers changes in the ferrite of the as-cast samples and inside the HAZ of the welded ones can be attributed to the existence of residual stresses (RS) in the ferritic matrix and assist in estimating the HAZ’s width.展开更多
The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano...The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.展开更多
A systematic account of micro-textures and a few compositional profiles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995, from Barren Island Volcano, NE India ocean, are presented fo...A systematic account of micro-textures and a few compositional profiles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995, from Barren Island Volcano, NE India ocean, are presented for the first time. The identified micro-textures can be grouped into two categories： （i） Growth related textures in the form of coarse/fine-sieve morphology, fine-scale oscillatory zoning and resorption surfaces resulted when the equilibrium at the crystal-melt interface was fluctuated due to change in temperature or H20 or pressure or composition of the crystallizing melt; and （ii） morphological texture, like glomerocryst, synneusis, swallow-tailed crystal, microlite and broken crystals, formed by the influence of dynamic behavior of the crystallizing magma （convection, turbulence, degassing, etc.）. Each micro-texture has developed in a specific magmatic environment, accordingly, a first order magma plumbing model and crystallization dynamics are envisaged for the studied lava unit. Magma generated has undergone extensive fractional crystallization of An-rich plagioclase in stable magmatic environment at a deeper depth. Subsequently they ascend to a shallow chamber where the newly brought crystals and pre-existing crystals have undergone dynamic crystallization via dissolution-regrowth processes in a convective self- mixing environment. Such repeated recharge-recycling processes have produced various populations of plagioclase with different micro-textural stratigraphy in the studied lava unit. Intermittent degassing and eruption related decompression have also played a major role in the final stage of crystallization dynamics.展开更多
During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron micr...During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron microsco- py, microstructure of the as-received X80 steel was confirmed to be acicular ferrite, while the microstructures of quenched, normalized and annealed X80 steels were lath bainite, granular ferrite and quasi-polygonal ferrite, respec- tively. After immersion in the simulated acidic soil solution for 48 h, corrosion rates of these four steels were deter- mined by mass loss measurements and corrosion products were examined by Raman spectroscopy and X-ray photoe lectron spectroscopy. Scanning vibrating electrode technique was used to characterize the micro-galvanic corrosion be- haviors of the synthetic bimetallic electrodes which were formed by coupling each of the simulated HAZ microstruc- tures with the as-received steel in direct physical and electric contact. It is demonstrated that the as-received steel acts as cathode in the as-received/quenched and as-received/normalized couples, while the annealed steel acts as cathode when coupling with the as received steel. The distinction of current density between the galvanic couples reduces with prolonging the immersion time.展开更多
The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the m...The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the micro-hardness of HAZ rises at the beginning and then decreases with increasing of t8/5 , whereas the impact toughness presents reverse trend. The distribution of precipitates in substrate has great influence on the impact toughness of HAZ. When the t8/5 is 40 s, chain-like precipitates lower the impact toughness of HAZ seriously.展开更多
Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distribut...Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distributed at the edge of faults,in poor sand bodies,and in insufficiently injected and produced areas.Therefore,the edge of faults is a major target for remaining oil enrichment and potential tapping.Based on the dynamic change of production from development wells determined by the injection-recovery relationship at the edge of faults,we analyzed the control of structural features of faults on remaining oil enrichment at the edge.Our results show that the macroscopic structural features and their geometric relationship with sand bodies controlled remaining oil enrichment zones like the edges of NNE-striking faults,the footwalls of antithetic faults,the hard linkage segments（two faults had linked together with each other to form a bigger through-going fault）,the tips of faults,and the oblique anticlines of soft linkages.Fault edges formed two types of forward microamplitude structures：（1） the tilted uplift of footwalls controlled by inverse fault sections and（2） the hanging-wall horizontal anticlines controlled by synthetic fault points.The remaining oil distribution was controlled by microamplitude structures.Consequently,such zones as the tilted uplift of the footwall of the NNW-striking antithetic faults with a fault throw larger than 40 m,the hard linkage segments,the tips of faults,and the oblique anticlines of soft linkage were favorable for tapping the remaining oil potential.Multi-target directional drilling was used for remaining oil development at fault edges.Reasonable fault spacing was determined on the basis of fault combinations and width of the shattered zone.Well core and log data revealed that the width of the shattered zone on the side of the fault core was less than 15 m in general;therefore,the distance from a fault to the development target should be larger than 15 m.Vertically segmented growth faults should take the separation of the lateral overlap of faults into account.Therefore,the safe distance of remaining oil well deployment at the fault edge should be larger than the sum of the width of shattered zone in faults and the separation of growth faults by vertical segmentation.展开更多
A three-dimensional local-scale P-velocity model down to 25 km depth around the main shock epicenter region was constructed using 83821 event-to-receiver seismic rays from 5856 aftershocks recorded by a newly deployed...A three-dimensional local-scale P-velocity model down to 25 km depth around the main shock epicenter region was constructed using 83821 event-to-receiver seismic rays from 5856 aftershocks recorded by a newly deployed temporary seismic network. Checkerboard tests show that our tomographic model has lateral and vertical resolution of -2 km. The high-resolution P-velocity model revealed interesting structures in the seismogenic layer： （1） The Guanxian-Anxian fault, Yingxiu-Beichuan fault and Wenchuan-Maoxian fault of the Longmen Shan fault zone are well delineated by sharp upper crustal velocity changes; （2） The Pengguan massif has generally higher velocity than its surrounding areas, and may extend down to at least -10 km from the surface; （3） A sharp lateral velocity variation beneath the Wenchuan-Maoxian fault may indicate that the Pengguan massif＇s western boundary and/or the Wenchuan-Maoxian fault is vertical, and the hypocenter of the Wenchuan earthquake possibly located at the conjunction point of the NW dipping Yingxiu-Beichuan and Guanxian-Anxian faults, and vertical Wenchuan-Maoxian fault; （4） Vicinity along the Yingxiu- Beichuan fault is characterized by very low velocity and low seismicity at shallow depths, possibly due to high content of porosity and fractures; （5） Two blocks of low-velocity anomaly are respectively imaged in the hanging wall and foot wall of the Guanxian-Anxian fault with a -7 km offset with -5 km vertical component.展开更多
Considering the heterogeneity of geomechanical materials, seismicity during brittle rock failure under compressive loading on the sample with an original weak zone is simulated by using rock failure process analysis c...Considering the heterogeneity of geomechanical materials, seismicity during brittle rock failure under compressive loading on the sample with an original weak zone is simulated by using rock failure process analysis code (RFPA2D). The run-through process of weak zone, the forming of new fault and associated micro-seismicities are studied. The modeling demonstrates the total process of source development of earthquake from deformation, micro-failure to collapse and the behavior of temporal-spatial distribution of micro-seismicities. The stress, strain and the temporal-spatial distribution of micro-seismicities life-likely portrayed the phenomena of localization and temporal-spatial transitions, which is similar to those observed in our real crust. Also, the results obtained in simulations are in agreement with or similar to the reported experimental observations.展开更多
Optical studies, backscattered electron images, secondary ion spectrometry and highprecision transmission electron imaging demonstrate that gold is strongly correlated with arsenic on a microscopic scale in the sedime...Optical studies, backscattered electron images, secondary ion spectrometry and highprecision transmission electron imaging demonstrate that gold is strongly correlated with arsenic on a microscopic scale in the sediment-hosted micro-disseminated gold deposits. The positive correlation between Au and As, despite varying Au/As ratio, is persistent in arsenian pyrite overgrowths and arsenopyrite. It is found that gold occurs in native state as submicro beads in association with arsenic-bearing sulfides. The extremely small grain size of gold may indicate a very rapid process of deposition.展开更多
The sub-vertical meso-and micro-structures and fabrics developed in coesite-bearing foliated eclogites in the Taohang （桃行） area, southeastern Shandong （山东）, China. The diagnostic structures and fabrics, includ...The sub-vertical meso-and micro-structures and fabrics developed in coesite-bearing foliated eclogites in the Taohang （桃行） area, southeastern Shandong （山东）, China. The diagnostic structures and fabrics, including penetrative foliation or mylonitic foliation containing mineral and stretching lineations, as well as sheath-like folds, appear to be the development of anastomosing UHP eciogite-facies shear belt arrays hosting massive eelogites. Textural relationships and mineral assem-blages indicate that the deformation of foliated eclogites developed closely after the formation of the massive eclogite, prior to the development of the granulite/amphibolite-facies symplectites and coronas, occurring over a very wide pressure range of （31-8）×10^2 MPa. It presents the structural records of the tectonometamorphic processes as being responsible for the earliest stages of exhumation of the UHP metamorphic rocks. Extensive regional field observations show that the meso-and micro-structures and fabrics recognized in the foliated eclogites at Taohang are remarkably similar or consistent in the whole Dabie （大别）-Sulu （苏鲁） UHP metamorphic belt. This article, thus, supports the idea that the earliest stages of exhumation of the UHP metamorphic rocks, from mantle depths to the Moho or the mantle-crust boundary layering, may be attributed mainly to a sub-vertical extrusion and ductile flow along the subduction channel, belonging to a syn-collision exhumation at about 235 to 220 Ma.展开更多
The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through...The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.展开更多
文摘Shielded Metal Arc Welding (SMAW) in Ductile Irons (DI) is often required by foundries for practical manufacturing reasons. The mechanical properties of the welded structures are strongly dependent on their HAZ’s width. A model based on the behaviour of the ferritic matrix of high-Si DIs in order to make an approach in measuring their HAZ’s width is developed in this study. A series of thermal treatments on 3.35 and 3.75 wt% Si as-cast DIs and spot SMAWs is applied on these materials. The applied SMAWs are done on non-preheated and preheated samples (150℃ - 300℃). For welding we modify the amperage (100 - 140A). The micro-hardness Vickers changes in the ferrite of the as-cast samples and inside the HAZ of the welded ones can be attributed to the existence of residual stresses (RS) in the ferritic matrix and assist in estimating the HAZ’s width.
基金supported by the Western-Caucasus Research Center
文摘The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.
文摘A systematic account of micro-textures and a few compositional profiles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995, from Barren Island Volcano, NE India ocean, are presented for the first time. The identified micro-textures can be grouped into two categories： （i） Growth related textures in the form of coarse/fine-sieve morphology, fine-scale oscillatory zoning and resorption surfaces resulted when the equilibrium at the crystal-melt interface was fluctuated due to change in temperature or H20 or pressure or composition of the crystallizing melt; and （ii） morphological texture, like glomerocryst, synneusis, swallow-tailed crystal, microlite and broken crystals, formed by the influence of dynamic behavior of the crystallizing magma （convection, turbulence, degassing, etc.）. Each micro-texture has developed in a specific magmatic environment, accordingly, a first order magma plumbing model and crystallization dynamics are envisaged for the studied lava unit. Magma generated has undergone extensive fractional crystallization of An-rich plagioclase in stable magmatic environment at a deeper depth. Subsequently they ascend to a shallow chamber where the newly brought crystals and pre-existing crystals have undergone dynamic crystallization via dissolution-regrowth processes in a convective self- mixing environment. Such repeated recharge-recycling processes have produced various populations of plagioclase with different micro-textural stratigraphy in the studied lava unit. Intermittent degassing and eruption related decompression have also played a major role in the final stage of crystallization dynamics.
基金Sponsored by National Natural Science Foundation of China(51171025,51131001)Beijing Postdoctoral Research Foundation of China(2013M540829)
文摘During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron microsco- py, microstructure of the as-received X80 steel was confirmed to be acicular ferrite, while the microstructures of quenched, normalized and annealed X80 steels were lath bainite, granular ferrite and quasi-polygonal ferrite, respec- tively. After immersion in the simulated acidic soil solution for 48 h, corrosion rates of these four steels were deter- mined by mass loss measurements and corrosion products were examined by Raman spectroscopy and X-ray photoe lectron spectroscopy. Scanning vibrating electrode technique was used to characterize the micro-galvanic corrosion be- haviors of the synthetic bimetallic electrodes which were formed by coupling each of the simulated HAZ microstruc- tures with the as-received steel in direct physical and electric contact. It is demonstrated that the as-received steel acts as cathode in the as-received/quenched and as-received/normalized couples, while the annealed steel acts as cathode when coupling with the as received steel. The distinction of current density between the galvanic couples reduces with prolonging the immersion time.
文摘The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the micro-hardness of HAZ rises at the beginning and then decreases with increasing of t8/5 , whereas the impact toughness presents reverse trend. The distribution of precipitates in substrate has great influence on the impact toughness of HAZ. When the t8/5 is 40 s, chain-like precipitates lower the impact toughness of HAZ seriously.
基金financial support from the Natural Science Foundation of China (Grant No. 41272151, 41472126)the Natural Science Foundation for Distinguished Young Scholars of Heilongjiang Province, China (Grant No. JC201304)+1 种基金the Joint Funds of the National Natural Science Foundation of China (Grant No. U1562214)the Program for Huabei Oilfield (Grant No. HBYT-CY5-2015-JS-127)
文摘Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distributed at the edge of faults,in poor sand bodies,and in insufficiently injected and produced areas.Therefore,the edge of faults is a major target for remaining oil enrichment and potential tapping.Based on the dynamic change of production from development wells determined by the injection-recovery relationship at the edge of faults,we analyzed the control of structural features of faults on remaining oil enrichment at the edge.Our results show that the macroscopic structural features and their geometric relationship with sand bodies controlled remaining oil enrichment zones like the edges of NNE-striking faults,the footwalls of antithetic faults,the hard linkage segments（two faults had linked together with each other to form a bigger through-going fault）,the tips of faults,and the oblique anticlines of soft linkages.Fault edges formed two types of forward microamplitude structures：（1） the tilted uplift of footwalls controlled by inverse fault sections and（2） the hanging-wall horizontal anticlines controlled by synthetic fault points.The remaining oil distribution was controlled by microamplitude structures.Consequently,such zones as the tilted uplift of the footwall of the NNW-striking antithetic faults with a fault throw larger than 40 m,the hard linkage segments,the tips of faults,and the oblique anticlines of soft linkage were favorable for tapping the remaining oil potential.Multi-target directional drilling was used for remaining oil development at fault edges.Reasonable fault spacing was determined on the basis of fault combinations and width of the shattered zone.Well core and log data revealed that the width of the shattered zone on the side of the fault core was less than 15 m in general;therefore,the distance from a fault to the development target should be larger than 15 m.Vertically segmented growth faults should take the separation of the lateral overlap of faults into account.Therefore,the safe distance of remaining oil well deployment at the fault edge should be larger than the sum of the width of shattered zone in faults and the separation of growth faults by vertical segmentation.
基金the Basic Research Foundation of the Institute of Geomechanics,CAGS(grant DZLXJK200707)Natural Science Foundation of China grant 40674058)
文摘A three-dimensional local-scale P-velocity model down to 25 km depth around the main shock epicenter region was constructed using 83821 event-to-receiver seismic rays from 5856 aftershocks recorded by a newly deployed temporary seismic network. Checkerboard tests show that our tomographic model has lateral and vertical resolution of -2 km. The high-resolution P-velocity model revealed interesting structures in the seismogenic layer： （1） The Guanxian-Anxian fault, Yingxiu-Beichuan fault and Wenchuan-Maoxian fault of the Longmen Shan fault zone are well delineated by sharp upper crustal velocity changes; （2） The Pengguan massif has generally higher velocity than its surrounding areas, and may extend down to at least -10 km from the surface; （3） A sharp lateral velocity variation beneath the Wenchuan-Maoxian fault may indicate that the Pengguan massif＇s western boundary and/or the Wenchuan-Maoxian fault is vertical, and the hypocenter of the Wenchuan earthquake possibly located at the conjunction point of the NW dipping Yingxiu-Beichuan and Guanxian-Anxian faults, and vertical Wenchuan-Maoxian fault; （4） Vicinity along the Yingxiu- Beichuan fault is characterized by very low velocity and low seismicity at shallow depths, possibly due to high content of porosity and fractures; （5） Two blocks of low-velocity anomaly are respectively imaged in the hanging wall and foot wall of the Guanxian-Anxian fault with a -7 km offset with -5 km vertical component.
基金The Development Program on National Key Basic Researches under the Project Mechanism and Prediction of Continental Strong Earthquakes (G19980407) State Natural Science Foundation (49974009).
文摘Considering the heterogeneity of geomechanical materials, seismicity during brittle rock failure under compressive loading on the sample with an original weak zone is simulated by using rock failure process analysis code (RFPA2D). The run-through process of weak zone, the forming of new fault and associated micro-seismicities are studied. The modeling demonstrates the total process of source development of earthquake from deformation, micro-failure to collapse and the behavior of temporal-spatial distribution of micro-seismicities. The stress, strain and the temporal-spatial distribution of micro-seismicities life-likely portrayed the phenomena of localization and temporal-spatial transitions, which is similar to those observed in our real crust. Also, the results obtained in simulations are in agreement with or similar to the reported experimental observations.
文摘Optical studies, backscattered electron images, secondary ion spectrometry and highprecision transmission electron imaging demonstrate that gold is strongly correlated with arsenic on a microscopic scale in the sediment-hosted micro-disseminated gold deposits. The positive correlation between Au and As, despite varying Au/As ratio, is persistent in arsenian pyrite overgrowths and arsenopyrite. It is found that gold occurs in native state as submicro beads in association with arsenic-bearing sulfides. The extremely small grain size of gold may indicate a very rapid process of deposition.
基金supported by the National Natural Science Foundation of China (Nos. 40372094 and 49972067)
文摘The sub-vertical meso-and micro-structures and fabrics developed in coesite-bearing foliated eclogites in the Taohang （桃行） area, southeastern Shandong （山东）, China. The diagnostic structures and fabrics, including penetrative foliation or mylonitic foliation containing mineral and stretching lineations, as well as sheath-like folds, appear to be the development of anastomosing UHP eciogite-facies shear belt arrays hosting massive eelogites. Textural relationships and mineral assem-blages indicate that the deformation of foliated eclogites developed closely after the formation of the massive eclogite, prior to the development of the granulite/amphibolite-facies symplectites and coronas, occurring over a very wide pressure range of （31-8）×10^2 MPa. It presents the structural records of the tectonometamorphic processes as being responsible for the earliest stages of exhumation of the UHP metamorphic rocks. Extensive regional field observations show that the meso-and micro-structures and fabrics recognized in the foliated eclogites at Taohang are remarkably similar or consistent in the whole Dabie （大别）-Sulu （苏鲁） UHP metamorphic belt. This article, thus, supports the idea that the earliest stages of exhumation of the UHP metamorphic rocks, from mantle depths to the Moho or the mantle-crust boundary layering, may be attributed mainly to a sub-vertical extrusion and ductile flow along the subduction channel, belonging to a syn-collision exhumation at about 235 to 220 Ma.
基金The project supported by the National Natural Science Foundation of China (19891180 and 19925211)Bai Ren Plan of CAS
文摘The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.
