| As a new type of lightweight material,rare-earth magnesium?Mg-RE?alloys not only have various advantages of traditional magnesium alloys,but also has high strength and good heat resistance.It is widely used in aerospace,automobile and 3C electronic products.Dynamic recrystallization?DRX?as the main grain refinement mechanism in magnesium alloys has an important influence on the mechanical properties and plastic forming ability.At present,the research on the factors affecting DRX behavior of Mg-RE alloy is mainly focused on deformation temperature,deformation degree and strain rate.However,the research on the effect of initial orientation on DRX behavior of Mg-RE alloy is still very rare.In this paper,Mg-13Gd-4Y-2Zn-0.5Zr?wt.%?alloy ingots were selected as the research materials.The magnesium alloy plate with base surface texture was prepared by homogenization treatment and plane strain compression.Rectangular samples with 0°,45°,and 90°normal directions?ND?of the magnesium alloy plate were used as the initial samples.The plane strain compression were carried out at different deformation degrees?reductions of10%,20%,30%,40%and 50%?,deformation temperatures?380°C,450°C and 520°C?and strain rates(0.001s-1 and 0.1s-1).The microstructure and texture of samples before and after the hot compression were characterized by electron backscatter diffraction?EBSD?.The influence of initial orientation on DRX behavior during the hot compression in Mg-RE alloy under different deformation conditions,and the type of slip mechanism opened during the hot compression deformation of samples with different initial orientations were investigated.The initial orientation how to affect DRX behavior by affecting the type of slip mechanism opened was discussed.The main research results are as following:1.After the hot compression deformation,the difference in area fraction of DRX grains in the samples with different initial orientations is that:the area fraction of DRX grains of the0°sample is the largest,followed by the 90°sample,and the 45°sample is the smallest.However,with the deformation degree?reduction?increases,the deformation temperature increases,and the strain rate decreases,the above-mentioned difference gradually decreases.2.The initial orientation affects DRX behavior by affecting the type of slip mechanism opened during the hot compressive deformation of the Mg-RE alloy.?1?After the hot compression deformation,the texture of the 0°sample not changes obviously,the c-axis of most grains is parallel to the compression direction,which indicates that the<c+a>cone slip is the most easy to open during the hot compression deformation.The CRSS of<c+a>cone slip is very large,which leads to the higher dislocation density and promotes the occurrence of DRX.Therefore,the area fraction of DRX grains of 0°sample is the largest.?2?After the hot compression deformation,the texture of 45°sample changes significantly,the c-axis of some grains is parallel to the compression direction,the c-axis of some grains is perpendicular to the compression direction,which indicates that the<a>base slip and<a>cylinder slip are the most easy to open during the hot compression deformation.The opening of<a>base slip and<a>cylinder slip makes the dislocation density significantly lower and inhibits the occurrence of DRX.Therefore,the area fraction of DRX grains of 45°sample is the smallest.?3?After the hot compression deformation,the texture of the 90°sample is not changed,the c-axis of most grains is perpendicular to the compression direction,which indicates that the<a>cylinder slip is the most easy to open during the hot compression deformation.The opening of the<a>cylinder slip reduces dislocation density and delays the occurrence of DRX.Therefore,the area fraction of DRX grains of 90°sample is between 0°and 45°. |
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