Non-basal dislocation nucleation site of solid solution magnesium alloy

固溶型マグネシウム合金の非底面転位生成サイト

染川 英俊*; Basha, D. A.*; Singh, A.*; 都留 智仁   ; 山口 正剛   

Somekawa, Hidetoshi*; Basha, D. A.*; Singh, A.*; Tsuru, Tomohito; Yamaguchi, Masatake

本論文では、固溶型MgY二元系合金を用いて粒界偏析の塑性変形への影響を評価した。変形後の微細組織観察から、底面転位とともに柱面の転位が観察され、これらはイットリウム元素が偏析した粒界から生成されることがわかった。第一原理計算を用いた二元系合金の材料特性を比較することによって、非底面すべりに対して低い臨界分解せん断応力と粒界偏析エネルギーが大きい合金元素が、粒界近傍の非底面転位を活性化することが明らかになった。

The effect of grain boundary segregation on plastic deformation was investigated using the MgY solid solution binary alloy. Deformed microstructural observations revealed many traces of prismatic dislocations as well as basal dislocations. These dislocations were nucleated at grain boundaries with segregation of yttrium element. By comparison of material factors of binary alloy, the alloying elements having low critical resolved shear stress (CRSS) of non-basal plane and large grain boundary (twin boundary) segregation energy led to activation of non-basal dislocations in the vicinity of grain boundaries. The MgCa alloy had similar material factors and showed the same deformed microstructures as those of the alloys containing rare-earth element, which indicate that calcium element is an alternative alloying element.