Effects of heat treatments on the structure and mechanical properties of Zr–30Ti alloys

In this research the effects of various heat treatments on the structure and mechanical properties of a Zr–30Ti alloy (in wt.%) were examined. A β solution treatment at 1100 °C/10 min was applied, after which the specimens were subjected to water quenching, air cooling or liquid-nitrogen quenching. Some of the specimens were heated in a vacuum furnace at 900 °C for 60 min and subsequently furnace-cooled. The experimental results indicated that these alloys obviously had different structures and mechanical properties when subjected to different heat treatment conditions. The as-cast Zr–30Ti alloys were comprised entirely of a β phase; whereas, the furnace-cooled specimens were dominated by equilibrium α phase. The ω phase was observed in furnace-cooled and air-cooled alloys, especially in the furnace-cooled alloy having the largest quantity of ω phase. It is noteworthy that the water-quenched Zr–30Ti alloy in β + α phase exhibited the highest bending strength/modulus ratios, some as large as 20. Moreover, the elastic recovery capability of the water-quenched alloy (20.4°) was much greater than that of the as-cast Zr–30Ti (9.8°). In the current search for better implant materials, the Zr–30Ti alloy treated by water quenching appears to be a promising candidate due to its low modulus, ductile property, excellent elastic recovery capability and reasonably high strength.