In this work, deformation characteristics under indentation testing of metastable β-type titanium-molybdenum alloys were investigated. Ti-14mass%Mo and Ti-20mass%Mo were used to reveal influences of molybdenum content upon indentation behavior. It was found that the traces, which appeared in the surrounding area of indentation, of Ti-14Mo and Ti-20Mo were mainly caused by mechanical twining and crystal slip, respectively. The results also revealed that the dominant deformation mechanism of Ti-Mo alloys influences not only on the piling up around the indentation but also on the evaluated hardness, due to restriction of deformation area by mechanical twinning.
