Precipitates and alloying elements distribution in near alpha titanium alloy Ti65

Precipitates, including silicides and Ti3Al (alpha(2)) phase, and alloying elements distribution in a near alpha titanium alloy Ti65 (Ti-5.8Al-4.0Sn-3.5Zr-0.5Mo-0.3Nb- 1.0Ta-0.4Si-0.8W-0.05C) after solution treatment and aging process were characterized by using transmission electron microscopy (TEM) and atom probe tomography (APT). Quantitative composition analysis and TEM observation indicate that the silicides fit to (Ti, Zr)(6)(Si, Sn)(3). Zr exhibits a beta-stabilizing effect in near alpha titanium alloys but is weaker than other beta stabilizing elements. The enriching tendency of the alloying elements in the retained beta phase is in the order of Zr < Nb < Ta < Mo < W. The experimental results are rationalized by the relative stability of alloying elements in the alpha and beta phases and the mobility of these atoms in the matrix. An enrichment of Si in the alpha(2) phase over the alpha matrix phase is noticed, which is attributed to the lower formation energy of Si in the alpha(2) phase. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.