查看更多>>摘要：Metastable high entropy alloys possesses excellent ductility and toughness, but its low strength hinders its engineering applications. Therefore, many studies have been carried out to improve the strength of metastable high entropy alloys while maintaining high ductility. In this paper, a new high entropy alloy is fabricated by selective laser melting (SLM) with the addition of Si powder into Fe50Mn30Co10Cr10 metastable high entropy alloy powders, with compositions (Fe50Mn30Co10Cr10)(100-x)Si-x (x = 0, 1, 3, 5). The results show that the yield strength and ultimate tensile strength of Si-containing metastable high-entropy alloys gradually increase with the increase of Si elements, and the performance is far better than that of without Si addition. The Si element increases the metastability of the gamma(FCC) phase in the high-entropy alloy, and promotes the phase transformation induced plasticity by adjusting the twinning strain during the deformation process; so that the total elongation of the material prepared by SLM can reach 30% and above. The combined effect of multiple strengthening mechanisms such as dislocation, deformation twinning, and phase transformation has greatly increased the strength of high-entropy alloys. In addition, the excellent strength-ductility combination of the alloy containing Si element indicates that the composition has good printability for laser additive manufacturing, which can provide a reference for expanding the diversification of high-entropy alloys in the additive manufacturing process.
查看更多>>摘要：In this study, three medium entropy alloys (MEAs), TiNbZr, Ti1.5Nb1.5Zr and Ti1.5NbZr1.5 were designed and investigated to be applied as biomedical materials. The results showed that the alloys prepared by arc melting have a typical dendrite microstructure, caused by elemental segregation during solidification. With composition changes, the partition of the constituting elements behaves differently. The microstructure inhomogeneity and chemical segregation could be greatly reduced by homogenization treatment. The MEAs show good compressive ductility (>40%) and yield strength comparable to or even superior to those of the commercially used biomedical alloys (e.g., 316 stainless steel and pure titanium), which are mainly contributed from the solid-solution strengthening effect. In addition, these MEAs exhibit acceptable Young's modulus ranging from 80 to 93 GPa by nano-indentation tests. The alloys also show excellent corrosion resistance in the phosphate buffer saline (PBS) solution and favorable cyto-compatibility, which are comparable to or even superior to pure titanium and/ or Ti-6Al-4V alloys. Based on these properties, the Ti-Nb-Zr MEAs show a promising potential in biomedical applications. The results in this study could be instructive for further alloy design of such biomedical MEAs.
NSTL
Elsevier