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

In this study, the effects of vanadium (V) addition on the microstructures and mechanical properties of hot-rolled Zr-9Al-chi V alloys (chi = 0, 2 and 4 at. %) were systematically investigated. Microscopic analyses indicated that the microstructures of hot-rolled Zr-9Al-chi V alloys were sensitive to the V content. The hot-rolled Zr-9Al alloy was completely dynamically recrystallized and consisted of the a phase only, whereas the hot-rolled Zr-9Al-2V alloy consisted of partially recrystallized alpha and transformed beta (alpha' + beta). 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 beta grains, in which equiaxed a and acicular alpha '' 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: beta ->alpha ''.