Tensile properties and plastic deformation modes ofβ Zr-Nb alloys

Abstract

Tensile properties and plastic deformation modes ofβ zirconium-niobium alloys were investigated at 290 and 77 K in the wide composition range from metastable to stableβ phase. Three types of plastic deformation modes, {332}〈113〉 twinning, {112}〈111〉 twinning and slip, were observed depending on alloy composition and temperature. {332}〈113〉 twinning, which occurs in metastableβ zirconium alloys, is related to the stability ofβ phase toω decomposition and leads to low yield stress and large elongation. On the other hand, {112}〈111〉 twinning, which appears in stableβ zirconium alloys, results from high critical stress for slip due to solution hardening and high Peierls stress and does not affect tensile properties significantly. The results obtained for zirconium-alloys are similar to those forβ titanium alloys, strongly suggesting that {332}〈113〉 twinning is an important plastic deformation mode which is common toβ phase alloys containing athermalω phase.