Refractory high-entropy alloys:A focused review of preparation methods and properties

In recent years,high-entropy alloys(HEAs)have become prominent metallic materials due to their unique design strategies and excellent mechanical properties.The HEAs-inherent high-entropy,lattice-distortion,sluggish-diffusion,and cocktail effects make HEAs maintain high strength,oxidation resistance,corrosion resistance,wear resistance,and other excellent comprehensive properties,showing stronger competitiveness relative to traditional alloys.Refractory high-entropy alloys(RHEAs)are considered as a new kind of high-temperature materials with great application prospects due to their excellent mechanical properties and have the potential to replace nickel-based superalloy as the next generation of high-temperature materials.We reviewed the research status and preparation methods of RHEAs in recent years,including the metallurgical smelting,powder metallurgy,magnetron sputtering,and additive manufacturing technologies.The microstructure and phase-transformation process of RHEAs were analyzed.The mechan-ical properties and main strengthening and toughening mechanisms of RHEAs,such as solid-solution strengthening,precipitation strengthening,and the transformation-induced plasticity(TRIP),were discussed,and the deformation mechanism of RHEAs was revealed.The properties of RHEAs,including high strength,oxidation resistance,corrosion and wear resistance were reviewed.RHEAs will meet the huge market demand in the engineering materials field,but there are still many challenges,such as the tradeoff between high strength and high ductility,structural design,and performance optimization of RHEAs with brittle BCC structures.We believe that this combination of knowledge may shape the future of RHEAs and break through the mutually exclusive conundrum of high strength and high toughness for RHEAs.

Biomedical applications of the powder-based 3D printed titanium alloys:A review

3D printing technology is a new type of precision forming technology and the core technology of the third industrial revolution.The powder-based 3D printing technology of titanium and its alloys have received great attention in biomedical applications since its advantages of custom manufacturing,costsaving,time-saving,and resource-saving potential.In particular,the personalized customization of 3D printing can meet specific needs and achieve precise control of micro-organization and structural design.The purpose of this review is to present the most advanced multi-material 3D printing methods for titanium-based biomaterials.We first reviewed the bone tissue engineering,the application of titanium alloy as bone substitutes and the development of manufacturing technology,which emphasized the advantages of 3D printing technology over traditional manufacturing methods.What is more,the optimization design of the hierarchical structure was analyzed to achieve the best mechanical properties,and the biocompatibility and osseointegration ability of the porous titanium alloy after implantation in living bodies was analyzed.Finally,we emphasized the development of digital tools such as artificial intelligence,which provides new ideas for the rational selection of processing parameters.The 3D printing titanium-based alloys will meet the huge market demand in the biomedical field,but there are still many challenges,such as the trade-off between high strength and low modulus,optimization of process parameters and structural design.We believe that the combination of mechanical models,machine learning,and metallurgical knowledge may shape the future of metal printing.