Activation Volume for Interdiffusion in B2 Type Intermetallic Compounds NiAl and FeAl

摘要

Activation volume for interdiffusion, ΔV-tilde , in B2 type intermetallic compounds NiAl (40 ～ 49 at%Al) and FeAl (40 ～ 50 at%Al) has been obtained above 0.75 Tm (Tm: melting temperature of alloys) by measuring the interdiffusion coefficient under the pressure from 0.1 MPa to 5 GPa. AV in NiAl shows almost constant value of 1.0 V0(Va: molar volume of alloys), suggesting that the divacancy mechanism is dominant at higher temperature region. On the other hand, AF in FeAl increases from 0.6 to 0.8～0.9 Vo with increasing temperature, showing that the contribution of divacancies to diffusion increases with increasing temperature. Diffusion mechanisms in NiAl and FeAl have been discussed with the help of our experimental data on intrinsic diffusion in them.