Influence of solution temperature on phase transformation of TC21 alloy

In TC21 alloy, the influence of solution treatment temperature on phase transformation has been investigated. When solution treatment was conducted at temperature above 840 °C, orthorhombic α″ martensite was formed. Moreover, the α2 phase was observed after solution treatment between 1000 °C and 920 °C for 1 h. Below 840 °C, the β phase was stable, no martensitic occurred. Crystallographic analysis suggests that the principal strains of martensitic transformation decrease with the solution treatment temperature decreasing. The microhardness of TC21 alloys on examination increased with the solution treatment temperature decreasing firstly, and then decreased, below 840 °C, the microhardness increased again with the solution treatment temperature.