Abstract
Ti-Mo alloys/composites are expected to be the next-generation implant material with low moduli but without toxic/allergic elements.However,synthesis mechanisms of the Ti-Mo biomaterials in Selective Laser Melting(SLM)vary according to raw materials and fundamentally influence material performance,due to inhomogeneous chemical compositions and stability.Therefore,this work provides a comparative study on microstructure,mechanical and wear performance,and underlying thermal mechanisms of two promising Ti-Mo biomaterials prepared by SLM but through different synthesis mechanisms to offer sci-entific understanding for creation of ideal metal implants.They are(i)Ti-7.5Mo alloys,prepared from a conventional Ti/Mo powder mixture,and(ii)Ti-7.5Mo-2.4TiC composites,in-situ prepared from Ti/Mo2C powder mixture.Results reveal that the in-situ Ti-7.5Mo-2.4TiC composites made from Ti/Mo2C powder mixture by SLM can produce 61.4％more β phase and extra TiC precipitates(diameter below 229.6 nm)than the Ti-7.5Mo alloys.The fine TiC not only contributes to thinner and shorter β columnar grains under a large temperature gradient of 51.2 K/μm but also benefits material performance.The in-situ Ti-7.5Mo-2.4TiC composites produce higher yield strength(980.1±29.8 MPa)and ultimate compressive strength(1561.4±39 MPa)than the Ti-7.5Mo alloys,increasing by up to 12.1％.However,the fine TiC with an aspect ratio of 2.71 dominates an unfavourable rise of elastic modulus to 91.9±2 GPa,44.7％higher than the Ti-7.5Mo alloys,which,nevertheless,is still lower than the modulus of traditional Ti-6A1-4V.While,TiC and its homogeneous distribution benefit wear resistance,decreasing the wear rate of the in-situ Ti-7.5Mo-2.4TiC composites to 6.98 x 10-4 mm3 N-1 m-1,which is 36％lower than that of the Ti-7.5Mo alloys.Therefore,although with higher modulus than the Ti-7.5Mo alloys,the SLM-fabricated in-situ Ti-7.5Mo-2.4TiC composites can expect to provide good biomedical application potential in cases where combined good strength and wear resistance are required.
基金项目
China Scholarship Council(201806830109)
NETL
NSTL
万方数据