Martensitic transformation in a α + β–Ti alloy after cryogenic treatment and its influencing to low elastic modulus biomaterials

Abstract

The high strength titanium alloy is one of the most popular α + β-Ti type alloy and well responsive to the microstructure mainly depends on the processing history, heat treatment and selective faster cooling treatments. It has many engineering applications like military application, biomedical implant and aerospace application. The cryogenic treatment (CT) was typically done for faster cooling at low temperature (−20 to −100 °C) after solution treatment at 860 °C for 1 h then immediately quenched into liquid nitrogen bath with control manner. Subsequently, another identical sample quenched into the water to cool room temperature. After successfully solution treated both samples again preferred for ageing treatment at 500 °C for 5 h then air cooling. The examination of microstructures by SEM analysis revealed that after double steps heat treatment shows very fine α and β phases, with needle shape α are decomposed from α′ martensite tend to speed up by TiN or VN precipitates enhanced strength in the matrix. As well as, vanadium content is one of the important factors for martensite formation after solution treatment in the α + β phase field. The results show that after double steps heat treatment in CT obtained optimum mechanical properties such as 0.2% proof strength (PS) of 790 MPa, ultimate tensile strength (UTS) of 1200 MPa, strain (ε) of 70%, reduction area (RA) of 16.76%, and PS to UTS ratio of 0.66, respectively. To intuitive study estimate the effect in water quenching (WQ) as well as cryogenic treatment on microstructures and mechanical properties of high strength Ti-Al-V ternary alloy, which is potentially used in aerospace and structural applications owing to a high specific strength and high corrosion resistance. Meanwhile, after faster cooling in CT that martensite transformation tends to exhibit low elastic modulus for beneficial to orthopaedic implants in the human body.