Microstructural,mechanical and shape memory characterizations of Ti-Mo-Sn alloys

As a β stabilizing element in Ti-based alloys,the effect of Mo on phase constitution,microstructure,mechanical and shape memory properties was investigated.Different compositions of Ti-xMo-3Sn alloys(where x=2,4,6,at.%) were prepared by arc melting.A binary composition of Ti-6 Mo alloy was also prepared for comparison.Ti-xMo-3Sn alloys show low hardness and high ductility with 90% reduction in thickness while Ti-6 Mo alloy shows high hardness,brittle behavior,and poor ductility.Field emission scanning electron microscopy(FESEM) reveals round morphology of athermal ω(ωath) precipitates.The presence of ωath phase is also confirmed by X-ray diffraction(XRD)in both as-cast and solution-treated and quenched conditions.The optical microscopy(OM) and FESEM show that the amount of martensite forming during quenching decreases with an increase in Mo content,which is also due to β→ω transformation.The hardness trends reinforce the presence of ωath too.The shape memory effect(SME) of 9% is the highest for Ti-6 Mo-3Sn alloy.The SME is trivial due to ωath phase formation;however,the increase in SME is observed with an increase in Mo content,which is due to the reverse transformation from ωath and the stress-induced martensitic transformation.In addition,a new and very simple method was designed and used for shape memory effect measurement.