The effects of the extrusion process and CaO addition amount on microstructure, mechanical, and corrosion properties of AZ31 alloys were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), standard tensile testing, and so on. The grain size of AZ31 or AZ31-1%CaO alloy becomes larger with increasing extrusion temperature. The grain size of AZ31-1%CaO alloy is much smaller than that of AZ31 alloy at the same extrusion temperature. In addition, the formation of the Al₂Ca phase caused by CaO addition refines the grain size, and the recrystallization of AZ31-1%CaO alloy is improved significantly. The recrystallization grains distribute more uniformly as the increase of extrusion ratio, and the completely recrystallized grains distribute uniformly in the form of equiaxed crystals with an extrusion ratio of 9. Tensile testing results show that extruded AZ31-1%CaO alloy at the extrusion temperature of 300 °C and an extrusion ratio of 9 exhibits the best mechanical properties. While corrosion properties of AZ31 alloys decreases due to the addition of CaO.

This paper investigated the effect of tungsten arc melting current on the microstructure and wear resistance of coatings prepared from high-entropy powder-cored wire, FeCrMnCuNiSi₁. A powder-cored wire of high-entropy composition was drawn by powder-cored wire-forming equipment, and a FeCrMnCuNiSi₁ high-entropy alloy coating was designed on the base material 40Cr by the tungsten arc fusion technique. The influence law and mechanism of melting current on the wear resistance of the coatings were obtained through analyzing the microstructure, physical phase, and wear resistance of the coatings prepared by different melting currents. At a melting current of 200A, the FeCrMnCuNiSi₁ coating exhibits fine equiaxed grains and a single BCC phase; the highest and average microhardness of the coating reach 790.36 HV and 689.73 HV, respectively, whose average microhardness is twice that of the base material. The wear rate of the coating is 2245.86 μm³/(N∙μm), which is only 8% of the base material and has excellent wear resistance. The FeCrMnCuNiSi₁ high-entropy alloy coating prepared by ordinary powder-cored wire-forming equipment and the tungsten arc cladding method has excellent performance and low cost, which can provide an essential basis for the development, preparation, and application of high-entropy alloy coatings.

Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue. As a regeneration implant material with great potential applications, in-situ Mg2Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg2Si reinforcements. The present study demonstrates that the primary and eutectic Mg2Si phase can be greatly modified by the yttrium (Y) addition. The size of the primary Mg2Si phases can be reduced to ~20 μm with an addition of 0.5 wt.% Y. This phenomenon is mainly attributed to the poisoning effect of the Y element. Moreover, wear resistance and tensile properties of the ternary alloy have also been improved by the Y addition. Mg-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears resistance. The ultimate tensile strength and the elongation of the alloy with 0.5 wt.% Y are 50% and 65% higher than those of the ternary alloy, respectively. Excessive Y addition (1.0 wt.%) deteriorates the tensile properties of Mg-Zn-Si alloy. The improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg2Si phases as well as the solid solution strengthening of the Y atoms. This study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.