The effect of alloying on the ordering processes in near-alpha titanium alloys

The substructure of near-alpha Ti-Al-Sn-Zr-Mo-Si alloys containing up to 12.5 at% aluminum was studied by transmission electron microscopy (TEM). It was shown that long-range order sections are formed at aging temperatures up to 500 degrees C in alloys, high in aluminum, and the ordered phase is formed by the nucleation and growth mechanism at 700 degrees C aging temperatures. Causes of changing the phase transformation mechanism have been discussed, and the relationship between the structure and properties of alloys, depending on modes of heat treatment has been analyzed. Also the influence of aluminides and suicides precipitation on the mechanical alloy properties after aging was examined. It was shown that the aluminide formation led to a slight hardening and a significant viscosity decrease. The silicide particles formation reduced the heat resistance properties, due to the depletion of the solid solution by silicon. (c) 2012 Elsevier B.V. All rights reserved.