To understand the mechanical and twinning behaviors of a fine-grained extruded Mg-8.0Al-0.1Mn-2.0Ca alloy under high-speed impact,impact tests were carried out using a split Hopkinson pressure bar,and microstructures ...To understand the mechanical and twinning behaviors of a fine-grained extruded Mg-8.0Al-0.1Mn-2.0Ca alloy under high-speed impact,impact tests were carried out using a split Hopkinson pressure bar,and microstructures at strains of 0.05,0.10 and 0.20 were obtained using a series of stop rings manufactured by high-strength steel.The stress response and twinning behavior are closely related to loading direction and applied strain rate.The true stress-true strain curves are s-shaped in extrusion direction(ED)and c-shaped in transverse direction(TD),showing apparent anisotropy,while the yield strength is insensitive to loading direction.Almost identical strain-rate sensitivity is demonstrated by the stress in ED and TD.Interestingly,de-twinning is apparent as the applied strain increases to 0.20,and it is enhanced with increasing the applied strain rate.In contrast,the twin density in ED samples is clearly higher than that in TD samples.By modifying the terms of strain hardening and strain rate hardening in the classical JC model,an optimized model is built,which can accurately predict the stress response behavior of the studied alloy under high-speed impact along ED and TD.The correlation coefficient(R)and average absolute relative error(AARE)are 98.63%and 0.0199 for ED,and 96.88%and 0.0202 for TD,respectively.展开更多
In the present study,room-temperature compression experiments and characterization experiments via optical microstructure(OM),X-ray diffractometer(XRD)and electron backscattered diffraction(EBSD)techniques were conduc...In the present study,room-temperature compression experiments and characterization experiments via optical microstructure(OM),X-ray diffractometer(XRD)and electron backscattered diffraction(EBSD)techniques were conducted on WE43 magnesium(Mg)alloy samples to investigate the grain size effect on twinning behavior.Three couples of solution treatments(823 K for 0.5 h,798 K for 8 h,823 K for 16 h,followed by water-quenching at~333 K)were adopted and these solutionized samples are with different grain sizes of 48.5,72.0 and 120.2μm,respectively.Results show that{10-12}extension twin(ET)and{11-21}ET serve as major twinning modes during plastic deformation.For all 7.7%-deformed samples,although the volume fractions of{10-12}ETs and{11-21}ETs increase with the increasing grain size.{10-12}ETs are in growth stage,while{11-21}ETs are mainly in nucleation stage and they still maintain narrow and parallel to each other.Besides,{10-12}ETs mainly contribute to the rotation of caxes of grains towards compression direction,while{11-21}ETs mainly contribute to the formation of a nearly ring-shaped texture component in(0002)pole figure.Twin variants analysis with the assistance of Schmid factor(SF)demonstrates that the activation of twin variants mainly obeys Schmid law.When only{10-12}ETs occur in individual grains,the maximum number of twin variants shows some positive relationship with the increasing grain size.By comparison,when both{10-12}ETs and{11-21}ETs occur in individual grains,the maximum numbers of twin variants are rarely influenced by the increasing grain size.展开更多
Two alloys with(T4-4h)and without(T4-8h)long-period stacking ordered(LPSO)phase were obtained by solution treatment of as-cast Mg-1Al-12Y alloy at 540℃ for 4 h and 8 h,respectively.The compressive tests(300-450℃,ε=...Two alloys with(T4-4h)and without(T4-8h)long-period stacking ordered(LPSO)phase were obtained by solution treatment of as-cast Mg-1Al-12Y alloy at 540℃ for 4 h and 8 h,respectively.The compressive tests(300-450℃,ε=0.01s^(-1))showed that the strengthening effect of LPSO in T4-4h alloy gradually disappeared with temperature increase.In addition,the corresponding compression deformation behavior of the two alloys was also investigated by electron backscatter diffraction(EBSD).It was found that the twinning of the two alloys was dominated by{1012}extension twins,and the large amount of lamellar LPSO in T4-4 h alloy inhibited the activation and growth of twins.The[0001]//compression direction(CD)texture formed after deformation is mostly attributed to the activation and growth of extension twins.By analyzing the activated twin variants,it was found that the activation of twin variants mainly depended on Schmid factor(SF).For twin variants with smaller SF,they may be activated due to local stress concentration.Based on the analysis results of in-grain misorientation axis(IGMA)and SF,the deformation mechanism of the alloys at elevated temperature is dominated by basal slip and non-basal slip.The stronger mechanical properties of T4-4h alloy than those of T4-8h are attributed to the obstruction of non-basal slip movement by LPSO.展开更多
The relationship of true stress and true strain of AZ41M magnesium alloy under twin-roll-cast （TRC） and hot compression was analyzed us- ing a Gleeble 1500 machine. Microstructural evolutions of the TRC magnesium al...The relationship of true stress and true strain of AZ41M magnesium alloy under twin-roll-cast （TRC） and hot compression was analyzed us- ing a Gleeble 1500 machine. Microstructural evolutions of the TRC magnesium alloy under different deformation conditions （strain, sWain rate and deformation temperature） were examined using optical microscopy and discussed. The relationship of true stress and true sWain pre- dicted that lower deformation temperature and higher sWain rate caused sharp strain hardening. Meanwhile, the flow stress curve turned into a steady state at high temperature and lower strain rate. The intermediate temperature and strain rate （623 K and 0.01 s^-1） is appropriate.展开更多
Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohes...Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohesive interface constitutive model based on the strain gradient plasticity theory. A systematic study of the strength and ductility for different grain sizes and twin lamellae distributions is performed. The results show that the material strength and ductility strongly depend on the grain size and the distribution of twin lamellae microstructures in the polycrystalline copper.展开更多
In this study,twinning behaviors of an extruded Mg-4.7Gd-3.4Y-1.2Zn-0.5Zr(wt%)alloy sheet along different directions extrusion direction(ED),45°:45°to ED and transverse direction(TD)under tension and compres...In this study,twinning behaviors of an extruded Mg-4.7Gd-3.4Y-1.2Zn-0.5Zr(wt%)alloy sheet along different directions extrusion direction(ED),45°:45°to ED and transverse direction(TD)under tension and compression were investigated.The results show that:(i)the twinning frequency of the extruded alloy sheet along different directions shows obvious anisotropy under both tension and compression while demonstrating opposite orders of ED>45°>TD under tension and TD>45°>ED under compression.Such anisotropic twinning frequencies are both in accord with their average twinning Schmid factor(TSF)orders.(ii)Under both tension and compression,the twinning variants(TVs)with the highest and the second highest TSF are frequently selected with priority.However,the TV selection law under tension has a certain difference from that of compression,which should be related to the TSF distributions of ortho-TV,meta-TV and para-TV under tension and compression.展开更多
The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were com...The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.展开更多
Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-off dilemma.In this work,we combined a novel alloy design principle,i...Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-off dilemma.In this work,we combined a novel alloy design principle,i.e.harvesting pronounced solid solution hardening(SSH)based on the misfit volumes engineering,and simultaneously,architecting the ductile matrix based on the valence electron concentrations(VEC)criterion,to fulfill an excellent strength-ductility synergy for the newly emerging high/medium-entropy alloys(HEAs/MEAs).Based on this strategy,Al/Ta co-doping within NiCoCr MEA leads to an efficient synthetic approach,that is minor Al/Ta co-doping not only renders significantly enhanced strength with notable SSH effect and ultrahigh strain-hardening capability,but also sharply refines grains and induces abnormal twinning behaviors of(NiCoCr)_(92)Al_(6)Ta_(2) MEA.Compared with the partially twinned NiCoCr MEA,the yield strength(σy)and ultimate tensile strength(σUTS)of fully twinned Al/Ta-containing MEA were increased by~102%to~600 MPa and~35%to~1000 MPa,respectively,along with good ductility beyond 50%.Different from the NiCoCr MEA with deformation twins(DTs)/stacking faults(SFs)dominated plasticity,the extraordinary strain-hardening capability of the solute-hardened(NiCoCr)_(92)Al_(6)Ta_(2) MEA,deactivated deformation twinning,originates from the high density of dislocation walls,microbands and abundance of SFs.The abnormal twinning behaviors,i.e.,prevalence of annealing twins(ATs)but absence of DTs in(NiCoCr)_(92)Al_(6)Ta_(2) MEA,are explained in terms of the relaxation of grain boundaries(for ATs)and the twinning mechanism transition(for DTs),respectively.展开更多
There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deforma...There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deformation behavior of AZ41M and ZK60M alloys, especially under the twin-roll casting (TRC) state. Meanwhile, the existing researches only focus on the grain refinement law of the magnesium alloys under deformation conditions, the deformation mechanism has not been revealed yet. The hot compression behavior of AZ41M and ZK60M magnesium alloys under the temperature and strain rate ranges of 250-400 ℃ and 0.001-1 s-1 are studied by thermal simulation methods using Gleeble 1500 machine and virtual simulation using finite element analysis software. Simulation results show that sine hyperbolic law is the most suitable flow stress model for wider deformation conditions. The most reasonable selected deformation conditions of ZK60M alloy is 350 oC/0.1 s-1 for TRC and 350 oC/1 s-1 for conventional casting (CC), while AZ41M alloy is 300 oC/0.01 s-1 for TRC and 350 oC/0.1 s-1 for CC. Deformation behavior and dynamic recrystallization (DRX) mechanism of them are analyzed at the same deformation conditions. The microstructures of AZ41M and ZK60M alloys are observed at different deformed conditions by optical microscopy (OM) and electron back scatter diffraction (EBSD) and it reveals the flow behavior and deformation mechanism of them. Working harden and work soften contribute to the activation of basal, non-basal slip systems which promote DRX. The proposed research reveals the deformation behavior and mechanism of the AZ41M and ZK 60M magnesium alloys and concludes their optimized deformation parameters and processes and provides a theory basis for their manufacturing and application.展开更多
In the present study,the influence of solute atoms together with dislocations at {101^-2} twin boundary（TB） on mechanical behavior of a detwinning predominant deformation in a Mg alloy AZ31 plate was systematically ...In the present study,the influence of solute atoms together with dislocations at {101^-2} twin boundary（TB） on mechanical behavior of a detwinning predominant deformation in a Mg alloy AZ31 plate was systematically studied.The results show that a large number of {101^-2} twins disappear during recompression along the normal direction.Both the TB-dislocation interaction and TB-solute-dislocation interaction can greatly enhance the yield stress of the recompression along the normal direction（ND）.However,the solute segregation at {1012} TBs with an intensive interaction with 〈a〉 dislocations cannot further enhance the yield stress of ND recompression.The samples with TB-dislocation interaction show a similar working hardening performance with that subjected to a TB-solute-dislocation interaction.Both the TB-dislocation interaction and TB-solute-dislocation interaction greatly reduce the value of work hardening peaks during a detwinning predominant deformation.展开更多
Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introd...Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introducing {10-12} twin lamellar structure. It has been found that higher strength and better ductility are obtained when tensile loading is perpendicular to the c axis of twin region of the twin lamellar structured sample, indicating that the plasticity improvement caused by twins depends on the special strain path. The fracture morphology of the twin lamellar structured sample shows a dimple fracture mode under tensile loading perpendicular to the c axis, while the cleavage fracture with river pattern has been observed in other fractured samples. Above experimental results indicate that the interaction of dislocations and twin lamellae may play an important role in improving mechanical properties of Mg alloy.展开更多
The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4...The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,＂Serration and noise behavior in advanced materials＂展开更多
基金supported by the National Natural Science Foundation of China(Nos.11872216 and 52071139)the Natural Science Foundation of Hunan Province(Nos.2019JJ50586 and 2019JJ50591)the Scientific Research Project of Hunan Provincial Department of Education(Nos.18B193 and 21B0471).
文摘To understand the mechanical and twinning behaviors of a fine-grained extruded Mg-8.0Al-0.1Mn-2.0Ca alloy under high-speed impact,impact tests were carried out using a split Hopkinson pressure bar,and microstructures at strains of 0.05,0.10 and 0.20 were obtained using a series of stop rings manufactured by high-strength steel.The stress response and twinning behavior are closely related to loading direction and applied strain rate.The true stress-true strain curves are s-shaped in extrusion direction(ED)and c-shaped in transverse direction(TD),showing apparent anisotropy,while the yield strength is insensitive to loading direction.Almost identical strain-rate sensitivity is demonstrated by the stress in ED and TD.Interestingly,de-twinning is apparent as the applied strain increases to 0.20,and it is enhanced with increasing the applied strain rate.In contrast,the twin density in ED samples is clearly higher than that in TD samples.By modifying the terms of strain hardening and strain rate hardening in the classical JC model,an optimized model is built,which can accurately predict the stress response behavior of the studied alloy under high-speed impact along ED and TD.The correlation coefficient(R)and average absolute relative error(AARE)are 98.63%and 0.0199 for ED,and 96.88%and 0.0202 for TD,respectively.
基金Project supported by the Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0252)Research and Innovation Team Cultivation Project of Chongqing University of Technology(2023TDZ010)。
文摘In the present study,room-temperature compression experiments and characterization experiments via optical microstructure(OM),X-ray diffractometer(XRD)and electron backscattered diffraction(EBSD)techniques were conducted on WE43 magnesium(Mg)alloy samples to investigate the grain size effect on twinning behavior.Three couples of solution treatments(823 K for 0.5 h,798 K for 8 h,823 K for 16 h,followed by water-quenching at~333 K)were adopted and these solutionized samples are with different grain sizes of 48.5,72.0 and 120.2μm,respectively.Results show that{10-12}extension twin(ET)and{11-21}ET serve as major twinning modes during plastic deformation.For all 7.7%-deformed samples,although the volume fractions of{10-12}ETs and{11-21}ETs increase with the increasing grain size.{10-12}ETs are in growth stage,while{11-21}ETs are mainly in nucleation stage and they still maintain narrow and parallel to each other.Besides,{10-12}ETs mainly contribute to the rotation of caxes of grains towards compression direction,while{11-21}ETs mainly contribute to the formation of a nearly ring-shaped texture component in(0002)pole figure.Twin variants analysis with the assistance of Schmid factor(SF)demonstrates that the activation of twin variants mainly obeys Schmid law.When only{10-12}ETs occur in individual grains,the maximum number of twin variants shows some positive relationship with the increasing grain size.By comparison,when both{10-12}ETs and{11-21}ETs occur in individual grains,the maximum numbers of twin variants are rarely influenced by the increasing grain size.
基金the financial support of Qinghai Provincial Key Laboratory of New Light Alloys(No.2022-ZJ-Y20)to carry out this research work.
文摘Two alloys with(T4-4h)and without(T4-8h)long-period stacking ordered(LPSO)phase were obtained by solution treatment of as-cast Mg-1Al-12Y alloy at 540℃ for 4 h and 8 h,respectively.The compressive tests(300-450℃,ε=0.01s^(-1))showed that the strengthening effect of LPSO in T4-4h alloy gradually disappeared with temperature increase.In addition,the corresponding compression deformation behavior of the two alloys was also investigated by electron backscatter diffraction(EBSD).It was found that the twinning of the two alloys was dominated by{1012}extension twins,and the large amount of lamellar LPSO in T4-4 h alloy inhibited the activation and growth of twins.The[0001]//compression direction(CD)texture formed after deformation is mostly attributed to the activation and growth of extension twins.By analyzing the activated twin variants,it was found that the activation of twin variants mainly depended on Schmid factor(SF).For twin variants with smaller SF,they may be activated due to local stress concentration.Based on the analysis results of in-grain misorientation axis(IGMA)and SF,the deformation mechanism of the alloys at elevated temperature is dominated by basal slip and non-basal slip.The stronger mechanical properties of T4-4h alloy than those of T4-8h are attributed to the obstruction of non-basal slip movement by LPSO.
基金supported by the Natural Science Foundation of Shandong Province (Nos Y2008F27 and ZR2009FL003)the S&T Developing Program of Shandong Province, China (2007GG10004013)the Doctoral Foundation of University of Jinan (XBS0830)
文摘The relationship of true stress and true strain of AZ41M magnesium alloy under twin-roll-cast （TRC） and hot compression was analyzed us- ing a Gleeble 1500 machine. Microstructural evolutions of the TRC magnesium alloy under different deformation conditions （strain, sWain rate and deformation temperature） were examined using optical microscopy and discussed. The relationship of true stress and true sWain pre- dicted that lower deformation temperature and higher sWain rate caused sharp strain hardening. Meanwhile, the flow stress curve turned into a steady state at high temperature and lower strain rate. The intermediate temperature and strain rate （623 K and 0.01 s^-1） is appropriate.
基金the National Natural Science Foundation of China (Nos. 10432050, 10428207, 10672163 and10721202)the Chinese Academy of Science through Grant KJCX-YW-M04.
文摘Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohesive interface constitutive model based on the strain gradient plasticity theory. A systematic study of the strength and ductility for different grain sizes and twin lamellae distributions is performed. The results show that the material strength and ductility strongly depend on the grain size and the distribution of twin lamellae microstructures in the polycrystalline copper.
基金Project supported by National Natural Science Foundation of China(52304402)Jiangxi Provincial Natural Science Foundation(20232BAB214058,20224BAB214044)。
文摘In this study,twinning behaviors of an extruded Mg-4.7Gd-3.4Y-1.2Zn-0.5Zr(wt%)alloy sheet along different directions extrusion direction(ED),45°:45°to ED and transverse direction(TD)under tension and compression were investigated.The results show that:(i)the twinning frequency of the extruded alloy sheet along different directions shows obvious anisotropy under both tension and compression while demonstrating opposite orders of ED>45°>TD under tension and TD>45°>ED under compression.Such anisotropic twinning frequencies are both in accord with their average twinning Schmid factor(TSF)orders.(ii)Under both tension and compression,the twinning variants(TVs)with the highest and the second highest TSF are frequently selected with priority.However,the TV selection law under tension has a certain difference from that of compression,which should be related to the TSF distributions of ortho-TV,meta-TV and para-TV under tension and compression.
基金National Natural Science Foundation of China(Nos.52004227,U22A20187,52201106)the China Postdoctoral Science Foundation(No.2020M683240)+1 种基金the Key Area Research and Development Program of Guangdong ProvinceChina(No.2020B090924002)。
文摘The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.
基金supported by the National Natural Science Foundation of China(Grant Nos.51722104,51790482,51621063 and 51625103)the 111 Project 2.0 of China(PB2018008)+1 种基金the National Key Research and Development Program of China(2017YFA0700701)the Fundamental Research Funds for the Central Universities for part of financial support(xtr022019004)。
文摘Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-off dilemma.In this work,we combined a novel alloy design principle,i.e.harvesting pronounced solid solution hardening(SSH)based on the misfit volumes engineering,and simultaneously,architecting the ductile matrix based on the valence electron concentrations(VEC)criterion,to fulfill an excellent strength-ductility synergy for the newly emerging high/medium-entropy alloys(HEAs/MEAs).Based on this strategy,Al/Ta co-doping within NiCoCr MEA leads to an efficient synthetic approach,that is minor Al/Ta co-doping not only renders significantly enhanced strength with notable SSH effect and ultrahigh strain-hardening capability,but also sharply refines grains and induces abnormal twinning behaviors of(NiCoCr)_(92)Al_(6)Ta_(2) MEA.Compared with the partially twinned NiCoCr MEA,the yield strength(σy)and ultimate tensile strength(σUTS)of fully twinned Al/Ta-containing MEA were increased by~102%to~600 MPa and~35%to~1000 MPa,respectively,along with good ductility beyond 50%.Different from the NiCoCr MEA with deformation twins(DTs)/stacking faults(SFs)dominated plasticity,the extraordinary strain-hardening capability of the solute-hardened(NiCoCr)_(92)Al_(6)Ta_(2) MEA,deactivated deformation twinning,originates from the high density of dislocation walls,microbands and abundance of SFs.The abnormal twinning behaviors,i.e.,prevalence of annealing twins(ATs)but absence of DTs in(NiCoCr)_(92)Al_(6)Ta_(2) MEA,are explained in terms of the relaxation of grain boundaries(for ATs)and the twinning mechanism transition(for DTs),respectively.
基金supported by National Natural Science Foundation of China (Grant No. U1134101)Shandong Provincial Natural Science Foundation of China (Grant No. ZR2011EMM003)
文摘There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deformation behavior of AZ41M and ZK60M alloys, especially under the twin-roll casting (TRC) state. Meanwhile, the existing researches only focus on the grain refinement law of the magnesium alloys under deformation conditions, the deformation mechanism has not been revealed yet. The hot compression behavior of AZ41M and ZK60M magnesium alloys under the temperature and strain rate ranges of 250-400 ℃ and 0.001-1 s-1 are studied by thermal simulation methods using Gleeble 1500 machine and virtual simulation using finite element analysis software. Simulation results show that sine hyperbolic law is the most suitable flow stress model for wider deformation conditions. The most reasonable selected deformation conditions of ZK60M alloy is 350 oC/0.1 s-1 for TRC and 350 oC/1 s-1 for conventional casting (CC), while AZ41M alloy is 300 oC/0.01 s-1 for TRC and 350 oC/0.1 s-1 for CC. Deformation behavior and dynamic recrystallization (DRX) mechanism of them are analyzed at the same deformation conditions. The microstructures of AZ41M and ZK60M alloys are observed at different deformed conditions by optical microscopy (OM) and electron back scatter diffraction (EBSD) and it reveals the flow behavior and deformation mechanism of them. Working harden and work soften contribute to the activation of basal, non-basal slip systems which promote DRX. The proposed research reveals the deformation behavior and mechanism of the AZ41M and ZK 60M magnesium alloys and concludes their optimized deformation parameters and processes and provides a theory basis for their manufacturing and application.
基金the financial support from the National Natural Science Foundation of China(Nos.51371203and 51571041)the National Key Basic Research Program of China(No.2013CB632204)
文摘In the present study,the influence of solute atoms together with dislocations at {101^-2} twin boundary（TB） on mechanical behavior of a detwinning predominant deformation in a Mg alloy AZ31 plate was systematically studied.The results show that a large number of {101^-2} twins disappear during recompression along the normal direction.Both the TB-dislocation interaction and TB-solute-dislocation interaction can greatly enhance the yield stress of the recompression along the normal direction（ND）.However,the solute segregation at {1012} TBs with an intensive interaction with 〈a〉 dislocations cannot further enhance the yield stress of ND recompression.The samples with TB-dislocation interaction show a similar working hardening performance with that subjected to a TB-solute-dislocation interaction.Both the TB-dislocation interaction and TB-solute-dislocation interaction greatly reduce the value of work hardening peaks during a detwinning predominant deformation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51071183,50890170 and 51271208)Basic Research of China(No.2010CB631004)Fundamental Research Funds for the Central Universities(No.CDJXS11132225)
文摘Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introducing {10-12} twin lamellar structure. It has been found that higher strength and better ductility are obtained when tensile loading is perpendicular to the c axis of twin region of the twin lamellar structured sample, indicating that the plasticity improvement caused by twins depends on the special strain path. The fracture morphology of the twin lamellar structured sample shows a dimple fracture mode under tensile loading perpendicular to the c axis, while the cleavage fracture with river pattern has been observed in other fractured samples. Above experimental results indicate that the interaction of dislocations and twin lamellae may play an important role in improving mechanical properties of Mg alloy.
文摘The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,＂Serration and noise behavior in advanced materials＂
