Title

Effect of pseudoelasticity of nanocrystalline titanium-nickel on wear

Date of Award

2007

Degree Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

Rights

CC BY-NC-ND 4.0

Abstract

The purpose of this research was to investigate the effect of nanocrystalline structure on shape memory (SM) property and pseudoelasticity (PE) of TiNi alloys with a special focus on the application in tribology. A binary TiNi alloy with 50.8at.% Ni was deformed using cold rolling and equal channel angular pressing (ECAP) method at 450 C to obtain the nanocrystalline structure. The martensitic transformation behaviour after deformation was studied by differential scanning calorimetry and the phase identification was done using X-ray diffraction. SM and pseudoelastic behaviour of the alloy was characterised by indentation and scratch testing. It was shown that after cold rolling and ECAP, the alloy showed higher pseudoelastic recovery. Even though the recovery was not complete, the depth recovery increased with the increasing amount of deformation strain. In addition, the alloy showed 6% SM strain recovery after ECAP processing. The effect of reduced grain size on the PE and SM was analysed and how these properties could be used to achieve a "self-healing surface" was discussed.