Hot tearing susceptibility(HTS)of Mg-2Zn-(3+0.5 x)Y-x Al(x=0,2 and 3 at%)alloys is predicted by using modified Clyne-Davies’model(CSC^(∗)).The solidification path,solidification characteristic temperatures and dendri...Hot tearing susceptibility(HTS)of Mg-2Zn-(3+0.5 x)Y-x Al(x=0,2 and 3 at%)alloys is predicted by using modified Clyne-Davies’model(CSC^(∗)).The solidification path,solidification characteristic temperatures and dendritic coherency solid fraction have been studied by double-thermocouple thermal analysis.The solidification contraction stress vs.temperature(and time)curves are measured by using a“T”type hot tearing permanent-mold.The results reveal that the CSC^(∗)prediction values are in good agreement with the experimental results.Moreover,Al_(2)Y phase acts as the heterogeneous nucleation core ofα-Mg and significantly influences the grain size.It has been observed that minimum grain size,optimal dendritic coherency and minimum HTS are exhibited by Mg-2Zn-(3+0.5 x)Y-x Al alloy(x=2).Furthermore,when Al content was increased to 3 at%,Al_(2)Y phase exhibited a peritectic reaction and transformed into a mixed structure of Al_(2)Y and Al+Al_(3)Y phases,which increased the HTS of the alloy due to reduced fine-grained Al_(2)Y content.展开更多
Mg-Y-Zn-Al alloys processed by rapidly solidified ribbon consolidation(RSRC)technique exhibit an exceptional mechanical performance indicating promising application potential.This material has a bimodal microstructure...Mg-Y-Zn-Al alloys processed by rapidly solidified ribbon consolidation(RSRC)technique exhibit an exceptional mechanical performance indicating promising application potential.This material has a bimodal microstructure consisting of fine recrystallized and coarse non-recrystallized grains with solute-rich stacking faults forming cluster arranged layers(CALs)and nanoplates(CANaPs),or complete long period stacking ordered(LPSO)phase.In order to reveal the deformation mechanisms,in-situ synchrotron X-ray diffraction line profile analysis was employed for a detailed study of the dislocation arrangement created during tension in Mg-0.9%Zn-2.05%Y-0.15%Al(at%)alloy.For uncovering the effect of the initial microstructure on the mechanical performance,additional samples were obtained by annealing of the as-consolidated specimen at 300 and 400℃ for 2 h.The heat treatment at 300℃ had no significant effect on the initial microstructure,its evolution during tension and,thus,the overall deformation behavior under tensile loading.On the other hand,annealing at 400℃ resulted in a significant increase of the recrystallized grains fraction and a decrease of the dislocation density,leading to only minor degradation of the mechanical strength.The maximum dislocation density at the failure of the samples corresponding to the plastic strain of 10-25% was estimated to be about 16-20×10^(14)m^(-2).The diffraction profile analysis indicated that most dislocations formed during tension were of non-basal and pyramidal types,what was also in agreement with the Schmid factor values revealed independently from orientation maps.It was also shown that the dislocation-induced Taylor hardening was much lower below the plastic strain of 3% than above this value,which was explained by a model of the interaction between prismatic dislocations and CANaPs/LPSO plates.展开更多
基金The authors would like to acknowledge the financial support from the National Natural Science Foundation of China(Nos.51571145 and 51504153)Innovation Talent Pro-gram in Sciences and Technologies for Young and Middle-aged Scientists of Shenyang(No.RC180111)+2 种基金Doctoral Scientific Research Foundation of Liaoning Province(No.20170520033)Youth Project of Liaoning Education Depart-ment(No.LQGD20170328)Natural Science Foundation of Liaoning Province(No.201602548).In addition,the authors would also like to thank Zhenglai Zhang from Zhejiang Hua Shuo Technology Co.,Ltd.and Ningbo City“Science and Technology Innovation 2025”major special project(new en-ergy vehicle lightweight magnesium alloy material precision forming technology research)funding support.
文摘Hot tearing susceptibility(HTS)of Mg-2Zn-(3+0.5 x)Y-x Al(x=0,2 and 3 at%)alloys is predicted by using modified Clyne-Davies’model(CSC^(∗)).The solidification path,solidification characteristic temperatures and dendritic coherency solid fraction have been studied by double-thermocouple thermal analysis.The solidification contraction stress vs.temperature(and time)curves are measured by using a“T”type hot tearing permanent-mold.The results reveal that the CSC^(∗)prediction values are in good agreement with the experimental results.Moreover,Al_(2)Y phase acts as the heterogeneous nucleation core ofα-Mg and significantly influences the grain size.It has been observed that minimum grain size,optimal dendritic coherency and minimum HTS are exhibited by Mg-2Zn-(3+0.5 x)Y-x Al alloy(x=2).Furthermore,when Al content was increased to 3 at%,Al_(2)Y phase exhibited a peritectic reaction and transformed into a mixed structure of Al_(2)Y and Al+Al_(3)Y phases,which increased the HTS of the alloy due to reduced fine-grained Al_(2)Y content.
基金financially supported by the International Visegrad Fund(project V4-Japan Joint Research Program,Ref.JP3936)the National Research,Development and Innovation Office(Contract No.:2019-2.1.7-ERANET-2021-00030)+1 种基金Support by the Ministry of Education,Youth and Sports of Czech Republic in the framework of Visegrad Group(V4)-Japan Joint Research Program-Advanced Materials under grant No.8F21011supported by JST SICORP Grant Number JPMJSC2109,Japan。
文摘Mg-Y-Zn-Al alloys processed by rapidly solidified ribbon consolidation(RSRC)technique exhibit an exceptional mechanical performance indicating promising application potential.This material has a bimodal microstructure consisting of fine recrystallized and coarse non-recrystallized grains with solute-rich stacking faults forming cluster arranged layers(CALs)and nanoplates(CANaPs),or complete long period stacking ordered(LPSO)phase.In order to reveal the deformation mechanisms,in-situ synchrotron X-ray diffraction line profile analysis was employed for a detailed study of the dislocation arrangement created during tension in Mg-0.9%Zn-2.05%Y-0.15%Al(at%)alloy.For uncovering the effect of the initial microstructure on the mechanical performance,additional samples were obtained by annealing of the as-consolidated specimen at 300 and 400℃ for 2 h.The heat treatment at 300℃ had no significant effect on the initial microstructure,its evolution during tension and,thus,the overall deformation behavior under tensile loading.On the other hand,annealing at 400℃ resulted in a significant increase of the recrystallized grains fraction and a decrease of the dislocation density,leading to only minor degradation of the mechanical strength.The maximum dislocation density at the failure of the samples corresponding to the plastic strain of 10-25% was estimated to be about 16-20×10^(14)m^(-2).The diffraction profile analysis indicated that most dislocations formed during tension were of non-basal and pyramidal types,what was also in agreement with the Schmid factor values revealed independently from orientation maps.It was also shown that the dislocation-induced Taylor hardening was much lower below the plastic strain of 3% than above this value,which was explained by a model of the interaction between prismatic dislocations and CANaPs/LPSO plates.
