Twinning and de-twinning are the salient deformation mechanisms in hexagonal close-packed(hcp)metals. The aim of this study was to examine and quantify the de-twinning process involving a reversible motion of twin bou...Twinning and de-twinning are the salient deformation mechanisms in hexagonal close-packed(hcp)metals. The aim of this study was to examine and quantify the de-twinning process involving a reversible motion of twin boundaries in an extruded AM30 magnesium alloy after re-compression along the normal direction(ND) of pre-compressed samples along the extrusion direction(ED). {1012} extension twins were first introduced at a compressive strain of 3.7% along the ED. The subsequent compressive deformation along the ND induced a gradual shrinkage of twins with increasing cumulative true strain,and the complete de-twinning occurred at a strain of ~7.7%. The twin width decreased linearly with increasing true strain. Texture measurements verified the rotation of c-axes of hcp unit cells towards the anti-compression direction due to {1012} extension twinning after compression along the ED, and a gradual return of c-axes to the initial orientation due to twin shrinking or de-twinning during the following compression along the ND. The {1012} twinning corresponded to the formation of new texture components C{1210}<0001> and D{0110}<0001> and a decrease in the initial texture components A{0001}<2110> and B{0001}<1010>, while the twin shrinking or de-twinning was characterized by a gradual vanishing of components C{1210}<0001> and D{0110}<0001> and an increase in the components A{0001}<2110> and B{0001}<1010>.展开更多
基金the Natural Sciences and Engineering Research Council of Canada (NSERC) and AUTO21 Network of Centres of Excellence for providing financial supportthe financial support by the Premier's Research Excellence Award (PREA), NSERC-Discovery Accelerator Supplement (DAS) Award, Automotive Partnership Canada (APC), Canada Foundation for Innovation (CFI)Ryerson Research Chair (RRC) Program
文摘Twinning and de-twinning are the salient deformation mechanisms in hexagonal close-packed(hcp)metals. The aim of this study was to examine and quantify the de-twinning process involving a reversible motion of twin boundaries in an extruded AM30 magnesium alloy after re-compression along the normal direction(ND) of pre-compressed samples along the extrusion direction(ED). {1012} extension twins were first introduced at a compressive strain of 3.7% along the ED. The subsequent compressive deformation along the ND induced a gradual shrinkage of twins with increasing cumulative true strain,and the complete de-twinning occurred at a strain of ~7.7%. The twin width decreased linearly with increasing true strain. Texture measurements verified the rotation of c-axes of hcp unit cells towards the anti-compression direction due to {1012} extension twinning after compression along the ED, and a gradual return of c-axes to the initial orientation due to twin shrinking or de-twinning during the following compression along the ND. The {1012} twinning corresponded to the formation of new texture components C{1210}<0001> and D{0110}<0001> and a decrease in the initial texture components A{0001}<2110> and B{0001}<1010>, while the twin shrinking or de-twinning was characterized by a gradual vanishing of components C{1210}<0001> and D{0110}<0001> and an increase in the components A{0001}<2110> and B{0001}<1010>.
