Influence of silicide and texture on the room temperature deformation size effect of Ti65 alloy sheets/foils and its constitutive model modification

In micro-scaled plastic deformation process such as micro-forming, material size effect is challenging to investigate and reveal using traditional material models. Since high-temperature titanium alloys have become the critical materials of micro-parts depending on outstanding mechanical properties, studying the effect of texture and silicide precipitate on size effect in microtensile deformation of a high-temperature titanium alloy is of great significance because the size effect of highly alloyed titanium alloys has been less studied. In the present study, various heating treatments were performed to regulate grain size and texture and obtain silicide precipitate. The room temperature tensile tests were carried out to investigate the effect of the texture and silicide precipitate on the size effect of plastic deformation behaviour. It is revealed that silicide precipitation in the heat-treated specimens can lead to a more obvious “smaller is weaker” phenomenon and the specimens with transverse textures show a better strength–ductility match. In addition, considering solution strengthening, grain boundary strengthening and precipitation strengthening, the material constitutive model is modified by the effect of silicide and texture on the size effect, allowing for an accurate description of the tensile deformation characteristics at the microscopic scale. The results of the physical experiments and the hybrid constitutive model provide a basis for understanding and further exploration of the microscale plastic deformation behaviour of high-temperature titanium alloys.