Electron backscatter diffraction(EBSD)is an orientation mapping technique,which has been widely used to study texture evolution and twinning behavior.This work aims to study the variant of{10¯12}twins during tens...Electron backscatter diffraction(EBSD)is an orientation mapping technique,which has been widely used to study texture evolution and twinning behavior.This work aims to study the variant of{10¯12}twins during tensile deformation of AZ31 Mg alloys.An in-situ tensile stage was used,and coupled with EBSD technique,the variants of twins can be analyzed without releasing the tensile stress.Based on the EBSD maps,the first and second smallest misorientation angles(M_(1)and M 2)between each active twin and respective potential variants were calculated,and the distribution of M_(1)values with tensile strain was obtained.The results indicated that{10¯12}twins were deviated from their ideal orientations with strain increased.The criteria of M_(1)<4°and M 2−M_(1)>2°were suggested to be applied to select the data points for reliable variant identification.Moreover,it confirmed that the deviation of twin relationship was ascribed to the profuse basal glide in matrices and/or twins.展开更多
This paper proposes a direct and simple method to identify the second twins from twinning variants by electron back scattered diffraction （EBSD）. To clarify the orientation relationship between the neighboring cryst...This paper proposes a direct and simple method to identify the second twins from twinning variants by electron back scattered diffraction （EBSD）. To clarify the orientation relationship between the neighboring crystals, the misorientation calculation by MATLAB software based on the EBSD data is also used. This method is generally applicable to predict the variants occurring in the nucleation and growth of the recrystallization or phase transformation process.展开更多
Deformation twinning serves as an important mode of plastic dissipation processes in nanoscale body-centered cubic(BCC)metals,but its origin and spatio-temporal features are mysterious.Here,applying in situ tensile ex...Deformation twinning serves as an important mode of plastic dissipation processes in nanoscale body-centered cubic(BCC)metals,but its origin and spatio-temporal features are mysterious.Here,applying in situ tensile experiments,we report a strong size effect on mediating the twinning behaviors and twin boundary(TB)-dislocation interaction mechanisms in BCC iron(Fe)nanowires(NWs).There exists a critical diameter(d)of∼2.5 nm,above which the deformation twinning rather than dislocation slip dominates the plasticity.Unlike the traditional reflection TBs,the intermediate isosceles TBs are consis-tently observed as mediated by the 1/12<111>partial dislocations.Moreover,we uncover two distinct TB-related deformation mechanisms,including twin variant re-orientation and TB cracking for NWs with d<17 nm and d>17 nm,respectively.Further molecular dynamics and statics simulations provide the basic underlying mechanisms for size-dependent plasticity,which have been largely overlooked in previous experimental investigations.Our findings highlight the importance of grain size in mediating the deformation behaviors in Fe,serving as possible guidance for exploring single-crystalline and poly-crystalline Fe-based materials(e.g.steel)with optimized mechanical performance.展开更多
In the present investigation,twinned substructures within lath martensite of two water quenched steels(0.2 wt.%C and 0.8 wt.%C)were studied.The lath martensite has typical hierarchical packet-block-lath with dislocati...In the present investigation,twinned substructures within lath martensite of two water quenched steels(0.2 wt.%C and 0.8 wt.%C)were studied.The lath martensite has typical hierarchical packet-block-lath with dislocation substructure.Besides,laths that are misoriented by<011>/70.5°or<111>/60° and bordered by{011}plane,namely twinned laths,are observed,of which the density increases and the scale decreases as more carbons were presented.Such twinned laths have body centered cubic(bcc)crystal structure,belonging to twinned variants following the classical Kurdjumov-Sachs(K-S)orientation relationship with respect to the parent austenite.Unlike bcc{112}<111>twins,twinned variants produce strong double diffraction and in turn the extra diffraction spots that are commonly observed in the martensite in steels with wide range of carbon contents.展开更多
将C含量(质量分数)分别为0.05%和0.4%的Fe-C-Mn-Si钢进行等温处理得到贝氏体组织,采用EBSD技术对奥氏体共格孪晶界上形成的贝氏体铁素体变体进行分析.结果表明,2种钢中的贝氏体铁素体与母相奥氏体均成近似K-S取向关系.奥氏体孪晶界两侧...将C含量(质量分数)分别为0.05%和0.4%的Fe-C-Mn-Si钢进行等温处理得到贝氏体组织,采用EBSD技术对奥氏体共格孪晶界上形成的贝氏体铁素体变体进行分析.结果表明,2种钢中的贝氏体铁素体与母相奥氏体均成近似K-S取向关系.奥氏体孪晶界两侧形成取向相同的变体对.此变体对形成后,孪晶界基本不再显现.晶体学分析表明,共格孪晶界两侧可能出现的变体对最多不超过3组,且这3组变体对的惯习面均与孪晶界平行,因此,贝氏体铁素体变体都将沿孪晶界生长.含C量为0.05%的Fe-C-Mn-Si钢中奥氏体孪晶界上只观察到一组贝氏体铁素体变体对的形成,这是因为C含量较低,贝氏体铁素体生长速度较快,消除了其它变体对的形核机会,先形核的变体对一旦形核就迅速覆盖整个孪晶面.而在含C量为0.4%的Fe C Mn-Si钢中,由于C含量较高,贝氏体铁素体生长速度较慢,3组变体对均有机会形核,因此,在孪晶界上可以观察到这3组变体对同时出现.展开更多
基金RL Xin would like to thank Prof.John J.Jonas for his helpful comments.This project was financially supported by the National Natural Science Foundation of China(Project no.51571045,51471039 and 51421001)Zhejiang Provincial Natural Science Foundation of China(LQ18E010004).
文摘Electron backscatter diffraction(EBSD)is an orientation mapping technique,which has been widely used to study texture evolution and twinning behavior.This work aims to study the variant of{10¯12}twins during tensile deformation of AZ31 Mg alloys.An in-situ tensile stage was used,and coupled with EBSD technique,the variants of twins can be analyzed without releasing the tensile stress.Based on the EBSD maps,the first and second smallest misorientation angles(M_(1)and M 2)between each active twin and respective potential variants were calculated,and the distribution of M_(1)values with tensile strain was obtained.The results indicated that{10¯12}twins were deviated from their ideal orientations with strain increased.The criteria of M_(1)<4°and M 2−M_(1)>2°were suggested to be applied to select the data points for reliable variant identification.Moreover,it confirmed that the deviation of twin relationship was ascribed to the profuse basal glide in matrices and/or twins.
基金financially supported by the National Natural Science Foundation of China (Nos.50901018 and 51304039)the Fundamental Research Funds for the Central Universities (No.N110402008)the Doctoral Fund of Ministry of Education of China (No.20090042120009)
文摘This paper proposes a direct and simple method to identify the second twins from twinning variants by electron back scattered diffraction （EBSD）. To clarify the orientation relationship between the neighboring crystals, the misorientation calculation by MATLAB software based on the EBSD data is also used. This method is generally applicable to predict the variants occurring in the nucleation and growth of the recrystallization or phase transformation process.
基金supported by the National Natural Science Foundation of China (Nos.52071237,12074290,51871169,52101021,and 12104345)the Natural Science Foundation of Jiangsu Province (No.BK20191187)+1 种基金the Young Top-notch Talent Cultivation Program of Hubei Province,the Science and Technology Program of Shenzhen (No.JCYJ20190808150407522)the China Postdoctoral Science Foundation (No.2019M652685).
文摘Deformation twinning serves as an important mode of plastic dissipation processes in nanoscale body-centered cubic(BCC)metals,but its origin and spatio-temporal features are mysterious.Here,applying in situ tensile experiments,we report a strong size effect on mediating the twinning behaviors and twin boundary(TB)-dislocation interaction mechanisms in BCC iron(Fe)nanowires(NWs).There exists a critical diameter(d)of∼2.5 nm,above which the deformation twinning rather than dislocation slip dominates the plasticity.Unlike the traditional reflection TBs,the intermediate isosceles TBs are consis-tently observed as mediated by the 1/12<111>partial dislocations.Moreover,we uncover two distinct TB-related deformation mechanisms,including twin variant re-orientation and TB cracking for NWs with d<17 nm and d>17 nm,respectively.Further molecular dynamics and statics simulations provide the basic underlying mechanisms for size-dependent plasticity,which have been largely overlooked in previous experimental investigations.Our findings highlight the importance of grain size in mediating the deformation behaviors in Fe,serving as possible guidance for exploring single-crystalline and poly-crystalline Fe-based materials(e.g.steel)with optimized mechanical performance.
基金supported financially by the Hundred Outstanding Creative Talents Projects in Hebei University,Chinathe Project Program of Heavy Machinery Collaborative Innovation Center,the National Natural Science Foundation(Grant No.51231006,51171182 and 51471039)。
文摘In the present investigation,twinned substructures within lath martensite of two water quenched steels(0.2 wt.%C and 0.8 wt.%C)were studied.The lath martensite has typical hierarchical packet-block-lath with dislocation substructure.Besides,laths that are misoriented by<011>/70.5°or<111>/60° and bordered by{011}plane,namely twinned laths,are observed,of which the density increases and the scale decreases as more carbons were presented.Such twinned laths have body centered cubic(bcc)crystal structure,belonging to twinned variants following the classical Kurdjumov-Sachs(K-S)orientation relationship with respect to the parent austenite.Unlike bcc{112}<111>twins,twinned variants produce strong double diffraction and in turn the extra diffraction spots that are commonly observed in the martensite in steels with wide range of carbon contents.
文摘将C含量(质量分数)分别为0.05%和0.4%的Fe-C-Mn-Si钢进行等温处理得到贝氏体组织,采用EBSD技术对奥氏体共格孪晶界上形成的贝氏体铁素体变体进行分析.结果表明,2种钢中的贝氏体铁素体与母相奥氏体均成近似K-S取向关系.奥氏体孪晶界两侧形成取向相同的变体对.此变体对形成后,孪晶界基本不再显现.晶体学分析表明,共格孪晶界两侧可能出现的变体对最多不超过3组,且这3组变体对的惯习面均与孪晶界平行,因此,贝氏体铁素体变体都将沿孪晶界生长.含C量为0.05%的Fe-C-Mn-Si钢中奥氏体孪晶界上只观察到一组贝氏体铁素体变体对的形成,这是因为C含量较低,贝氏体铁素体生长速度较快,消除了其它变体对的形核机会,先形核的变体对一旦形核就迅速覆盖整个孪晶面.而在含C量为0.4%的Fe C Mn-Si钢中,由于C含量较高,贝氏体铁素体生长速度较慢,3组变体对均有机会形核,因此,在孪晶界上可以观察到这3组变体对同时出现.
