Microstructure and Mechanical Properties of SPSed (Spark Plasma Sintered) Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 Bulk Alloys with and without WC Addition

Abstract

Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 bulk alloys with and without WC addition were fabricated by spark plasma sintering and crystallization of amorphous phase. Microstructure analysis indicates that Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 bulk alloy without WC addition has a ultrafine-grained microstructure with in situ precipitated ductile β-Ti(Nb) phase, composed of soft (Cu, Ni)-Ti₂ regions surrounded by hard β-Ti regions. The alloy exhibits high fracture strength of above 2000 MPa and remarkable plasticity of ∼21%. In contrast, Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 bulk alloys with WC addition consist of a microstructure of in situ precipitated ductile β-Ti regions surrounded by a mixed phase regions of (Cu, Ni)-Ti₂, TiC, WC and residual glassy phase. The alloys with WC addition display brittle facture behavior. The different plastic deformability for the fabricated bulk alloys with and without WC addition can be explained based on their distinctive microstructures.