Constrained deformation of molybdenum single crystals

Abstract

High-purity molybdenum single crystals were deformed at room temperature in both free compression and plane strain compression. In free compression, crystals were oriented with [100], [110] and [111] parallel to the compression axis. The orientations for plane strain compression were (110)[001], (110)[110], (100)[011] and (100)[010], with (hkl) being the plane of compression and [uvw] the elongation direction. Change in width of the specimen is suppressed by a channel. The resulting stress-strain (σ-ε) curves were converted to resolved shear stress: resolved shear strain (τ-γ) curves using the Taylor-Bishop-Hill analysis. It was found that the τ-γ curves do not form a narrow band if {110}〈111〉 slip is assumed. A narrow band is formed, however, if asymmetric {112}〈111〉 slip is assumed along with {110}〈111〉 slip, with τ 112 H = τ 110 = 1.3 τ 112 E , where τ 110, τ 112 H and τ 112 E are the CRSS for {110} slip, {112} slip in the antitwinning sense and {112} slip in the twinning sense respectively. Thus it may be concluded that the Schmid Law is obeyed in high-purity Mo deformed at room temperature by assuming a combination of asymmetric {112}〈111〉 and {110}〈111〉 slip systems.