Al-1.0%Mg_2Si合金の粒界近傍における局部変形に対する銅添加の影響 Effect of copper addition on localized deformation near grain boundaries in an Al-1.0 mass%Mg_2Si alloy
Age-hardened Al–1.0 mass%Mg<sub>2</sub>Si alloy (base alloy) and Al–1.0 mass%Mg<sub>2</sub>Si–0.46 mass%Cu alloy (0.5%Cu alloy) specimens were tensile-tested at room temperature. Localized deformation near grain boundaries in these alloy specimens were investigated by scanning tunneling microscopy (STM). The 0.5%Cu alloy specimen had intergranular fracture surface as the base alloy, although uniform elongation of the alloy was increased up to about 4% strain by copper addition. The surface topography of the "fold" in both the base and 0.5%Cu alloys were consistent with those of the Al–1.0 mass%Mg<sub>2</sub>Si alloy with 0.36 mass% excess silicon. Direction of the grain boundary motion in the base alloy was explained by the magnitude and direction of maximum resolved shear stress on the grain boundary plane (corresponding to <i>F</i>max), but in the 0.5%Cu alloy, it was not. Frequency of fold formation in the base alloy reached to about 40% of all triple points in the gauge area, while it was about 30% in the 0.5%Cu alloy. For about 80% of the steps at grain boundaries, the height (at ε≒4%) was less than 200 nm in the 0.5%Cu alloy.
軽金属 48(5), 207-211, 1998-05-30
The Japan Institute of Light Metals