The influence of Zr content on microstructure and precipitation of suicide in as-cast near alpha titanium alloys

摘要

The influence of Zr content on microstructure and precipitation of suicide in as-cast Ti-1100-xZr (x = 4, 6 wt.%) alloys was systematically investigated. The results demonstrate that the addition of 6 wt.% Zr promotes the essential refinement of alloy microstructures and the formation of TiSi and ternary (TiZr)6Si3 (S-2 type) silicides. The TiSi and S-2 type silicides are found to precipitate heterogeneously in the retained beta phase. The TiSi phase has specific orientation relationships with the retained (beta) phase: (102)(Tisi)//(1 (1) over bar0), [<(2)over bar41](Tisi)//[001](beta) and (100)(Tisi)/(101)(beta), [1<(1)over bar>1](Tisi)//[111](beta). The long axis direction of S-2 type silicide has geometric connection with the direction of plates of a phase due to the orientation relationships between the S-2 phase and the a phase: (01 (1) over bar0)S-2//(2 (11) over bar0)alpha, [2 (11) over bar3]S-2//[0001)alpha and (1010)S-2//1(1110)alpha, [1.213]S-2 //[1011]. It is also found that the Zr element added to titanium alloys affects the lattice parameters. (C) 201.4 Elsevier Inc. All rights reserved.