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High-entropy alloys having excellent properties are particularly suitable for the application as the filler metals in welding. In the present study, multi-component mixed powders of FeCoCrNiMn and CrFeNi2.4Al0.6, based on a high-entropy design, as well as the comparative 316L stainless steel powders, were used as the filler metals, to achieve the dissimilar welding between 304 stainless steel and SMA490BW steel by laser deposition welding. By comparative analysis of the microstructure and mechanical properties of three types of joints, the feasibility and weld-ability of the filler metal powders based on a high-entropy design were studied. It was found that the melting of base metal (BM) and weld metal dilution had an impact on the set high-entropy component in the weld zone. And high-entropy structures were achieved in the weld zone by using the powders of CrFeNi2.4Al0.6. Compared to the BM of SMA490BW steel, three types of joints presented a higher notched tensile strength and had a better corrosion resistance. The joint welded using the powders of CrFeNi2.4Al0.6 had the lowest hardness value in the weld zone, in which the joint was fractured during the notched tensile tests. The other two joints fractured near the notch in the SMA490BW steel side. Transgranular fracture and a typical dimple fracture were observed in the fractured joints. In this work, multi-component mixed powders of FeCoCrNiMn and CrFeNi2.4Al0.6, based on a high-entropy design, were used as the filler metals to achieve the dissimilar welding of 304 stainless steel to SMA490BW steel by laser deposition welding. And a detailed investigation of microstructures and mechanical properties of those dissimilar joints was carried out to explore the feasibility and weld-ability of the filler metal powders based on a high-entropy design.

Multipass friction stir processing (FSP) can result in a homogeneous microstructure and significant improvement in mechanical properties of magnesium alloys. Few studies have concentrated on the surface properties of Mg–Zn–Zr alloy during multipass FSP. The aim of this study was to investigate the microstructure evolutions as well as the effects on the surface corrosion and wear resistance of ZK60 plates during multipass FSP. An interesting finding is that FSP can significantly refine the grains and improve the surface properties of ZK60 alloy. However, subsequent passes of FSP cannot further reduce the grain size in the stir zone, but they cause an increase in the grain size in the ZK60 alloy. In addition, the subsequent passes of FSP are not beneficial, but rather are, harmful to the corrosion resistance of ZK60 alloy. There is little positive effect on the improvement in the wear resistance of ZK60 plates.

A dual-gradient bainite steel matrix composite was fabricated by direct laser deposition (DLD) method. The decomposition of WC (reinforcements) during DLD is utilized to adjust the gradient microstructure of the composite. Both the matrix morphology and the reinforcement distribution present obvious gradient variation along the deposition direction. The microhardness and impact toughness exhibit the opposite tendency from the bottom to top of the composite, which shows a good agreement with the gradient microstructure. The surface microhardness and impact toughness of the dual-gradient composite are 510 HV and 75 J/cm2, respectively. The hardness and toughness combination of the composite is superior to most steels for railway frog. The dual-gradient composite has great potential in improving the performance of railway frog.