Influence of the microstructure on the pseudoelasticity of a metastable beta titanium alloy

The pseudoelasticity of metastable Beta III titanium alloy, used for orthodontic applications, is obtained by cold wiredrawing. The role of the microstructure and the conditions of deformation on the stability of the β phase are studied in order to increase the strain recovery and to decrease the apparent modulus. The effects of a precipitate second phase, the grain size and the predeformation will be successively examined. The isothermal precipitation of α or ω phase does not improve the pseudoelastic effect. However, a structure with coarse grains, quenched from a temperature higher than the beta transus, associated with a uniaxial predeformation, increases the pseudoelasticity. This behavior is due to the variant reorientation of the martensite induced by the predeformation.