High strength and ductility titanium alloy with bimodal micro-spherical/ultrafine lamellar structure tailored by semi-solid isothermal processing technology

Abstract

In this paper, to obtain high strength and plasticity titanium alloy, a (Ti₇₈Fe₂₂)₈₉Nb₉Y₂ alloy was synthesized and tailored by semi-solid isothermal processing (SSIP). The experiment revealed that during the semi-solid treatment process, the microstructure of the alloy progressively transformed from dendritic to spherical crystals as the temperature and holding time increased. This transformation was accompanied by the dissolution of fine precipitates into the matrix. As a result, the alloy was composed of bimodal micro-spherical/ultrafine lamellar structure. Compression tests show that the compressive strength remains at 2551 MPa after holding at 1100 °C for 60 min, the plasticity reaches reached 50.5%. The shape factor SF and average size D a well as their correlation with plastic strain ε was also calculated and analyzed in detail.