Over the last few decades, the interest for titanium alloys has been continuously increasing for industrial applications, due to a promising combination of high strength, low density and good corrosion resistance. However, both a low ductility (typically <20%) and a lack of strain hardening still constitute a major drawback when compared to steels or Co-Cr based alloys, limiting their potential in advanced applications where combination of strength and large deformation is required. Consequently, there is a huge challenge in developing new titanium materials displaying improved combination of mechanical properties including high plastic deformation capacity.
In this work, results are presented on the design of a new family of titanium alloys with high ductility induced by combined transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) effects. Mechanical tests carried out on a binary and ternary β-metastable Ti based alloy designed by a formulation strategy based on the “d- electron alloy design” show a very high work hardening rate combinated with a high ductility of about 40%. In-situ synchrotron X-ray diffraction (SXRD) and transmission electron microscopy reveal a combined mechanical activation of intense mechanical twinning and both ω and α’’ phases stress induced precipitations.
Laboratoire de Physico-Chimie des surfaces, Groupe de Métallurgie Structurale (UMR 7045)