Microstructure and mechanical properties of new composite structured Ti–V–Al–Cu–Ni alloys for spring applications

New as-cast Ti–V–Cu–Ni–Al alloys with advantageous modulus of resilience and bioperformance were developed. Their microstructure is composed of a dendritic β-Ti phase and in-situ precipitated interdendritic compounds. The tough and ductile β-Ti phase exhibits a relatively low Young׳s modulus. Ultrafine intermetallics effectively strengthen the alloys. The effect of microstructure on tensile plasticity was studied on strained (in-situ) and fractured (ex-situ) samples in the scanning electron microscope. It was found that the ductility depends on the volume fraction/distribution of the intermetallic phases as well as local segregation. Already in the as-cast state Ti68.8V13.6Cu6Ni5.1Al6.5 exhibits a tensile strength of about 1250 MPa and a ductility of about 4.5%.