Evolution of Microstructure and Hardness of TC11 Titanium Alloy under Different Electroshocking Treatment Directions

Abstract

The effects of electroshocking treatment (EST) direction on microstructure and hardness of TC11 alloy (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) were investigated. The results indicated that the temperature of specimens under EST along the transverse direction (T-EST) was higher than that under EST along the vertical direction (V-EST). The studies reveal the higher quantity of needle-like α martensite (αM) phases precipitated in the specimen in the case of T-EST as compared with V-EST, with a more uniform distribution of αM phases. The average Vickers hardness of specimens under T-EST and V-EST with 0.06 s were 349.3 HV and 360.8 HV, respectively, which showed an obvious increase compared to the untreated specimen. The increase in hardness was ascribed to the dispersion strengthening of needle-like αM phase, and the dispersion strengthening effect on the specimen under T-EST with 0.06 s was more obvious than on the other specimens, which was caused by a large number of evenly distributed nucleation areas for the precipitation of the αM phase and uniform distribution of the αM phase. The results indicate that a different treatment direction of EST can promote the formation of different microstructures in TC11 alloy, which demonstrates that the effect of EST cannot be simply equated with heat treatment at the same temperature.