Corrosion and mechanical properties of a novel biomedical WN43magnesium alloy prepared by spark plasma sintering

Alloying of Mg with rare-earth(RE)elements proved to be beneficial for their in-vitro and in-vivo performance.In this work,a novel WN43(Mg-4 wt%Y-3 wt%Nd)alloy with a well-defined composition was prepared,where,unlike in the commercial WE43 alloy,the possibly harmful RE mischmetal was substituted by less toxic Nd.A modern spark plasma sintering(SPS)technique was used to effectively produce WN43 samples from atomized powders.Sintering temperatures of 400℃-550℃ and holding times of 3 or 10 min were used and wellcompacted final materials were successfully prepared.It was shown that a superior combination of corrosion and mechanical properties was attained in the samples sintered at 500℃ and 550℃,while the effect of sintering time was rather negligible.The performance of this material was exceptional within the group of Mg alloys prepared by powder metallurgy and comparable with conventionally prepared alloys.Moreover,it was shown that a great variety of mechanical and corrosion characteristics can be obtained by altering the SPS parameters so as to fulfill case-specific requirements typical of biomedical materials.Consequently,the novel WN43 alloy prepared by SPS seems to be a particularly suitable material for biomedical use.

A novel lean alloy of biodegradable Mg-2Zn with nanograins

Lean alloy(low alloyed)is beneficial for long-term sustainable development of metal materials.Creating a nanocrystalline microstructure is a desirable approach to improve biodegradability and mechanical properties of lean biomedical Mg alloy,but it is nearly impossible to realize.In the present study,the bulk nanocrystalline Mg alloy(average grain size:~70 nm)was successfully obtained by hot rolling process of a lean Mg-2wt.%Zn(Z2)alloy and both high strength((223 MPa(YS)and 260 MPa(UTS))and good corrosion resistance(corrosion rate in vivo:0.2 mm/year)could be achieved.The microstructure evolution during the rolling process was analyzed and discussed.Several factors including large strain,fine grains,strong basal texture,high temperature and Zn segregation conjointly provided the possibility for the activation of pyramidal<c+a>slip to produce nanocrystals.This finding could provide a new development direction and field of application for lean biomedical Mg alloys.