Special Features of Fracture of a Solid-State Titanium Alloy – Nickel – Stainless Steel Joint

Microstructure, nanohardness, and special features of fracture of three-phase titanium alloy and stainless steel joint through a nanostructural nickel foil are investigated. Uniformly distributed microcracks are observed in Ti 2 Ni and TiN 3 layers joined at temperatures above T = 700°C, whereas no microcracks are observed in the TiNi layer. This suggests that the reason for microcracking is an anomalously large change in the linear expansion coefficient of the TiNi layer during austenitic-martensitic transformation. Specimens subjected to mechanical tests at T = 20°C are fractured along different layers of the material, namely, in the central part of the specimen they are fractured along the Ti 2 Тi/TiNi interface, whereas at the edge they are fractured along the TiNi/TiNi 3 interface.