Microstructure and mechanical properties of novel Zr–Al–V alloys processed by hot rolling

Abstract

In this study, the effects of vanadium (V) addition on the microstructures and mechanical properties of hot-rolled Zr–9Al–χV alloys (χ = 0, 2 and 4 at. %) were systematically investigated. Microscopic analyses indicated that the microstructures of hot-rolled Zr–9Al–χV alloys were sensitive to the V content. The hot-rolled Zr–9Al alloy was completely dynamically recrystallized and consisted of the α phase only, whereas the hot-rolled Zr–9Al–2V alloy consisted of partially recrystallized α and transformed β (α′ + β). The tensile tests showed that the difference between the ultimate and yield strengths of the hot-rolled Zr–9Al alloy approximated 20 MPa, whereas that of the hot-rolled Zr–9Al–2V alloy was about 200 MPa. The evident strain hardening of the hot-rolled Zr–9Al–2V alloy was caused by the mechanical contrast between the soft and hard components of the microstructure. The hot-rolled Zr–9Al–4V alloy consisted of large elongated β grains, in which equiaxed α and acicular α" grains were distributed. The engineering stress–strain curve of the hot-rolled Zr–9Al–4V alloy exhibited a double-yielding behaviour, which was caused by stress-induced martensite phase transformation: β→α".