Strengthening of Mg and long-period stacking ordered phases in a Mg-Zn-Y alloy by hot-extrusion with low extrusion ratio

低押出比での熱間押出によるMg-Zn-Y合金のMgおよび長周期積層構造相の強化メカニズム

Harjo, S.   ; Gong, W.   ; 相澤 一也  ; 川崎 卓郎   ; 山崎 倫昭*

Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*

An as-cast sample and two hot-extruded samples with different extrusion ratios (R) of MgZnY alloy containing the HCP matrix (Mg) and the long-period stacking ordered phase (LPSO) of about 25-vol%, were used in tensile deformation in situ neutron diffraction experiments, to elucidate the effects of uniquely different microstructural evolutions in Mg and LPSO with varying the R value to the mechanical properties. Mg behaved as the soft phase and LPSO as the hard phase, and hot-extrusion improved the strength of both. At the R value of 5.0, a bimodal microstructure was created in Mg, increasing largely the yield strength of Mg. With increasing the R value to 12.5, the bimodal microstructure of Mg collapsed and the yield strength of Mg decreased. However, the strength of LPSO increased monotonously with increasing the R value due to the developments of kink bands and texture.