Surface nano-crystallisation and mechanical properties of Ti[sbnd]Ta composite materials after surface mechanical grinding treatment

Abstract

Surface mechanical milling generates gradient nano-structure surfacial layers that enhance the mechanical properties of titanium (Ti)–tantalum(Ta) composites for medical implants. Herein, the effect of surface mechanical grinding treatment (SMGT) on the surface nano-crystallisation of TiTa laminated composites was investigated in terms of micro-structure and Coherent Scattering Regions (CSRs) size using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A strengthening effect was verified using a micro-hardness tester and tensile testing machine, and the fracture mechanism was analysed through fracture observation. The experimental results showed that gradient nano-structures were formed on the surface of the TiTa laminated composites after SMGT, with the smallest CSRs size of the outer surface layer of approximately 13.3 ± 0.4 nm. The plastic deformation mechanism of the TiTa laminated composites during SMGT was a dislocation cutting mechanism. The micro-hardness and tensile strength of the TiTa laminated composites increased after SMGT up to 440 HV and 1097.528 MPa, respectively. The fracture mechanism of the TiTa laminated composites after SMGT was a combination of ductile fracture and quasi-cleavage fracture mechanisms. After SMGT, the TiTa laminated composite performed well and exhibited excellent potential for use in biomaterials.