Fine-scale strengthening swirls: Creatively combining different alloys using additive manufacturing methods has the potential to produce materials with interesting properties. Zhang et al . use laser powder bed fusion to combine small amounts of 316L stainless steel into Ti64 titanium alloy. This process creates an alloy with a distinctive microstructure that retains high strength while substantially improving ductility. The design strategy should be useful for improving mechanical properties in other alloy system as well. —BG

Microstructures and phase compositions of as-cast and extruded ZK60-xBi (x = 0–1.64) alloys were investigated. Meanwhile, the tensile mechanical property and hardness were tested. With increasing the Bi content, the as-cast microstructure is first refined obviously, and then becomes coarse slightly. New small block compound which is rich in Zr, Zn, Bi and poor in Mg increases gradually, and MgZn2 phase decreases gradually. The second phase mainly precipitates along the grain boundary. The as-cast tensile mechanical property is first enhanced obviously, where the tensile strength σb, yield strength σ0.2 and elongation δ can reach 265 MPa, 151 MPa and 13.5% for ZK60-0.23Bi alloy, respectively, then remains the high value for ZK60-(0.37–1.09)Bi alloys, and finally decreases obviously for ZK60-1.64Bi alloy. After hot extrusion, the obvious dynamic recrystallization occurs. Broken block compound distributes along the extrusion direction by zonal shape. The average grain size can reach only 4–6 μm. The extruded tensile mechanical property is enhanced significantly, where σb, σ0.2 and δ are at the range of 345–360 MPa, 285–300 MPa and 15.5–19.5%, respectively. Extruded tensile fracture exhibits a typical character of ductile fracture

The microstructures, mechanical properties, and thermal conductivity (TC) of Al-2Fe-xCo (x = 0~0.8) alloys in as-cast, homogeneous annealed, and cool rolled states are systematically studied. Results indicate that appropriate Co modification (x ≤ 0.5) simultaneously improves the thermal and mechanical properties of as-cast Al-2Fe alloys. The improvement of TC is attributed to ameliorating the morphology of primary Al₃Fe phases from needles to short rods and fine particles, which decreases the scattering probability of free electrons during the electronic transmission. However, further increasing the Co content (x = 0.8) decreases the TC due to the formation of a coarse plate-like Al₂FeCo phase. Besides, the thermal conductivity of annealed Al-2Fe-xCo alloys is higher than that of as-cast alloys because of the elimination of lattice defects and spheroidization of Al₃Fe phases. After cool rolling with 80 % deformation, thermal conductivity of alloys slightly increases due to the breaking down of Al₂FeCo phases. The rolled Al-2Fe-0.3Co alloy exhibits the highest thermal conductivity, which is about 225 W/(m·K), approximately 11 % higher than the as-cast Al-2Fe sample. The ultimate tensile strength (UTS) and elongation (EL) of as-cast Al-2Fe-0.5Co (UTS: 138 MPa; EL: 22.0 %) are increased by 35 % and 69 %, respectively, compared with those of unmodified alloy (UTS: 102 MPa; EL: 13.0 %).