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 beta solution treatment at 1100 degrees 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 degrees C for 60 mm 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 beta phase; whereas, the furnace-cooled specimens were dominated by equilibrium alpha phase. The omega phase was observed in furnace-cooled and air-cooled alloys, especially in the furnace-cooled alloy having the largest quantity of omega phase. It is noteworthy that the water-quenched Zr-30Ti alloy in beta + alpha 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 degrees) was much greater than that of the as-cast Zr-30Ti (9.8 degrees). 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. (C) 2010 Elsevier Inc. All rights reserved.