Crystal Structure and Hardness of TiAl Phase Containing Zirconium

Synthesis of ternary L10 compounds of Ti–Al–Zr system and their mechanical properties

“…3(c). Kasahara et al also reported the composition dependence of the lattice parameters and the c/a ratio for a limited range of the Ti-Al-Zr system [3]. The present results are generally in agreement with theirs.…”

“…Kasahara et al investigated the phase diagram of the ternary Ti-Al-Zr system near the composition of TiAl in detail [3]. The single ␥-phase region they obtained after 1 week annealing at 1273 K was much narrower than that given in Fig.…”

“…4 only for the single ␥-phase alloys. In this plot, hardness values for binary Ti-Al ␥-phase have been taken from literature [3]. It is found that the hardness increases with increasing Zr concentration.…”

Critical Assessment of the Al-Ti-Zr System

“…[62] Interdiffusion coefficients for Ti-rich b(Ti,Zr) at 1000°C and 1200°C have been determined in (Ref 63). Pure Al at 25°C [80] b(Ti), \20-38.5 at.% Al [27] Dissolves * 20 at.% Zr at 1000°C [24] c TiAl, (L1 0 ), \ 1456 tP4 P 4 /mmm AuCu a = 400.0 c = 407.5 at 50 at.% Al [88] a = 408.0 c = 408.7 *42 at.% Ti, * 47 at.% Al, * 11 at.% Zr [71] a = 397.4 c = 407.2 41.5 at.% Ti, 50.6 at.% Al, 7.9 at.% Zr [24] 46.5-* 73 at.% Al [27] Dissolves * 7.9 at.% Zr at 1000°C [24] Dissolves * 13 at.% Zr at 1274°C [ 65.5-67.0 at.% Al [27] Dissolves 11.5 at.% Zr at 1000°C [24] Dissolves 11.2 at.% Zr at 800°C [25] 1d-APS (Ti 74.2-75.5 at.% Al [27,42] Dissolves 7.5 at.% Zr at 1000°C [24] b(Zr), [52] After annealing the stoichiometric composition at 1200°C [52] Ti 2 AlZr, (D0…”

“…Therefore, alloys may have been supersaturated in Zr from the melting process at high temperatures and therefore the reported solid solubility may be too high. The solid solubility range of TiAl has also been examined on 21 alloys heat treated at 1000°C for 168 h. [71] Phases were analysed by XRD and compositions of phases were established by EPMA, but only lattice constants for TiAl are given and compositions can only be read for TiAl from a figure. According to this study the maximum solid solubility for Zr in TiAl could be about 11 at.% at about 47 at.% Al.…”