Diffusion reactions in titanium/Inconel-600 system

Abstract

The interdiffusion reactions in the Ti/Inconel-600 system in the temperature range 973–1153 K have been investigated by employing both the optical metallography and the electron probe microanalysis techniques. At 973 K the reaction zone showed the presence of solid solution phases like Ni-based (Fe, Cr, Ti) phase and titanium-based solid solution α-Ti. The two intermetallic phases, viz. TiNi(Fe, Cr) and Ti 2Ni are also observed. At 1023 K the reaction zone shows the formation of the two intermetallic phases, viz. TiNi(Fe, Cr) and Ti 2Ni along with solid solution phases such as Ni-based (Fe, Cr, Ti) phase and titanium-based solid solution β-Ti. At still higher temperatures (1073–1153 K), however, along with the solid solution phases such as Ni-based (Fe, Cr, Ti) phase and titanium-based solid solution β-Ti only one intermetallic phase, TiNi 3 (Fe, Cr), is formed. The temperature dependence of the reaction constants, K, m/s 1/2, derived from the layer growth kinetics, can well be expressed as for Ni-rich phase K=3.06×10 −5 exp(−262.16/RT), m/s 1/2 for TiNi 3( Fe, Cr) K=3.49×10 −5 exp(−240.96/RT), m/s 1/2 for β-Ti K=1.25×10 −6 exp(−983.80/RT), m/s 1/2. Here activation energy is expressed in kJ/mol. The interdiffusion parameters and the diffusion paths have also been established by employing these data.