Strong work hardening in a high niobium-containing TiNi-based bulk glassy alloy composite

Abstract

In this study, a high niobium-containing bulk glassy alloy composite Ti41Ni39Nb17.5Al2.5 consisting of amorphous, B2-TiNi and β-Nb phases was fabricated through in situ precipitation strategy by utilizing copper-mold suction casting. Upon compressive loading, the composite alloy showed a pronounced average plastic strain of (17.6 ± 3.5)% and a high fracture strength of (2279 ± 33) MPa together with a strong work-hardening deformation behavior. The volume fraction of the amorphous phase in the composite was determined to be around 23 vol%. The work softening caused by the formation of shear bands can be compensated by the work hardening arising from the pile-ups of dislocation and severe lattice distortion in the precipitated crystals and thereby stabilize the plastic deformation of the composite material. The findings imply that the room-temperature mechanical properties of bulk glassy alloy composites can be well tailored by selecting suitable reinforcers.