Pressure dependence of Zr diffusion in the equiatomic B.C.C. TiZr alloy

Abstract

AbstractPositive as well as negative activation volumes have been measured in the past for self‐diffusion in “anomalous” b.c.c. metals. To contribute to this problem and to obtain further information on the diffusion mechanism in b.c.c. transition metals the pressure dependence of diffusion of 95Zr is measured in the equiatomic b.c.c. TiZr alloy at 1003 and 1493 K in the pressure range up to 14.4 × 108 Pa. The rather small but positive activation volumes ΔV = 0.31 ± 0.06Ω and ΔV = 0.35 ± 0.10Ω, respectively, are obtained. The results are in conflict with negative ΔV values reported for this alloy by Smirnov et al., however, they agree very well with ΔV of self‐diffusion in β‐Ti. Within the limits of error ΔV is independent of temperature which indicates that only one diffusion mechanism is operating despite of the strongly curved Arrhenius relations of 95Zr and 44Ti diffusion in TiZr alloy. The present results confirm a monovacancy mechanism in group IVA b.c.c. metals.