Investigation of martensitic transformations by ultrasonic and acoustic emission techniques

Abstract

Acoustic emission (AE) daring martensitic transformation in nltinol, indium-cadmium, and indium-thallium alloys has been investigated and. the results have been compared with ultrasonic data of the same alloys. In indium-thallium and indium-cadmium alloys, acoustic emission is generated by a face-centred cubic ↔ face-centred tetragonal phase transition. On cooling, 'nitinol undergoes the diffusionless transition (like the indium-thallium alloys) from a body-centred cubic to a monoclinic structure. Elastic behaviour of TiNi and In-Tl alloys in the vicinity of the martensitic transformation is briefly discussed in the light of previous work (Pace, 1970 and Gunton,1973). A qualitative interpretation of acoustic emission from martensitic transformations has been outlined.