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The effects of heat extrusion processing of spray forming TiCp/ZA35 composites on extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate had been studied by artificial neural network (ANN). The artificial neural network model was created for heat extrusion processing. The input parameters of the ANN model were extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate. The output of the ANN model was ultimate tensile strength. The model can be used for the prediction of properties of spray forming TiCp/ZA35 composites as functions of processing parameters. It can also be used for the optimization of the processing parameters. The ANN results are in good agreement with experimental phenomena, the biggest relative error and coincidence rate is less than 1.8% and 0.986. The optimized heat extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate are 22415 MPa, 315 ° C and 8 mm•s-1 respectively, and the tensile strength of spray forming TiCp/ZA35 composites is 486.7 MPa. The reinforcement phase MnAl6 whisker or particle is precipitated in the grains due to the indirect aging treatment of composites by hot extrusion. Dispersion strengthen and dislocation strengthen contribute a combination factor to increase the room temperature mechanical properties of the hot extruded TiCp/ZA35 composites, which is 38.3% higher than that of TiCp/ZA35 composites without heat extrusion. [ABSTRACT FROM AUTHOR]

The study focused on investigating the impact of rare earth element Gd content on both the microstructure and mechanical properties of FeCrNiCuTi 0.4 Gd x (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.12, and 0.15, in mole ratio) high-entropy alloys, as well as elucidating the underlying mechanisms involved. The microstructure analysis revealed that the alloy exhibited a diphase structure consisting of FCC and BCC phases at low Gd content, and precipitation of the Cu 5 Gd phase occurred alongside the FCC and BCC phases at x = 0.05. The phase evolution of the current alloy system was assessed using the Ω - δ, △χ, and VEC (valence electron concentration) criteria. The mechanical properties indicated that the Vickers hardness increased with the increase of Gd content. Additionally, the compressive strength, yield strength, and plastic strain exhibit an initial increase followed by a decrease, while the average friction coefficient and wear demonstrated an initial increase followed by a subsequent decrease. The fracture mechanism shifted from plastic fracture to ductile fracture, ultimately transitioning to dissociative fracture with ductile fracture as the predominant mode. Similarly, the wear mechanism progressed from abrasive wear to a combination of abrasive wear with oxidation wear. The strengthening mechanisms of the present alloys included solid solution strengthening, fine crystal strengthening, and second-phase strengthening. • Rare earth element Gd was doped in FeCrNiCuTi 0.4 HEA. • Doping Gd improved the hardness, strength, and wear resistance of the HEAs. • The mechanisms included solid solution, fine crystal and second-phase strengthening. [ABSTRACT FROM AUTHOR]

The objective of this study is to modulate the size of intermetallic compounds to increase the strength of Al–Ag composites. In this study, we prepared Al–Ag composites using plasma-activated sintering (PAS). The effect of the applied current on the nucleation barrier of the Al/Ag alloy phase was investigated. The strengthening mechanism of Ag-reinforced Al matrix composites was explored. We found that two alloy phases, Ag 2 Al and Ag 3 Al, were generated in the Al–Ag composites. The alloy phases distributed at the grain boundaries strengthened the Al–Ag composites by enhancing the dislocation density in the matrix and by impeding dislocation motion. The ultimate tensile strength and yield strength of the Al–7Ag composite increased by 60.1% and 166%, respectively, compared with those of pure Al. Moreover, we calculated the contribution of each strengthening mechanism to the overall yield strength. The applied current lowered the nucleation barrier of the alloy phase and facilitated the nucleation process. [ABSTRACT FROM AUTHOR]

• Al-Mg-Li-Sc-Zr alloy was prepared by rapid solidification and ingot metallurgy. • Rapid solidification improves the mechanical properties of Al-Mg-Li-Sc-Zr alloy. • An excellent ultimate tensile strength of 352 MPa was obtained for the HIPed alloy. • Two-stage homogeneous treatment promoted the precipitation of Al 3 (Sc Zr) dispersoids. The microstructural evolution and mechanical properties of Al-Mg-Li-Sc-Zr alloys fabricated by ingot metallurgy (IM) and gas atomization (GA) with hot isostatic pressing (HIP) were investigated. The results showed that the as-cast alloy exhibits a coarse grain microstructure with large amounts of Al 2 MgLi and primary Al 3 (Sc, Zr) particles in the matrix. While a fine and uniformly structured HIPed alloy with a relative density of 99.9% can be obtained at 400 °C for 2 h, and no primary Al 3 (Sc, Zr) phase nor macro-segregation existed in the HIPed alloy. After a two-stage homogenization treatment, the Al 3 Li, Al 2 MgLi, and AlLi phases dissolved into the matrix, and simultaneously dense Al 3 (Sc, Zr) dispersoids precipitated in the two alloys. The number fraction of the Al 3 (Sc, Zr) phase in the HIPed alloy was much higher than that in the as-cast alloy. An excellent ultimate tensile strength of 352 MPa was obtained for the HIPed alloy, an increase of approximately 14% compared with the as-cast alloy. The increased strength in the HIPed alloy is mainly attributed to grain boundaries, precipitation, and solid-solution strengthening mechanisms. [ABSTRACT FROM AUTHOR]

Discontinuously reinforced 3D network structured Ti6Al4V (TC4) matrix composites with multilayer graphene (MLG) were fabricated via 3D dynamic mixing and spark plasma sintering (SPS) at high pressures (250–500 MPa). The interface microstructure, mechanical properties and strengthening mechanisms were systematically studied with various MLG contents. Experimental results exhibited that MLG can be relative uniformly dispersed onto the surface of TC4 powders by the 3D dynamic mixing method, SPS parameter of 700 °C-500 MPa caused weak interface bonding between MLG and Ti matrix, and 900 °C-250 MPa was determined as the optimal sintering condition. Appropriate ratio of in-situ generated TiC phase with approximately 30 vol% retained MLG at the interface was beneficial to the interface bonding. The compressive strength of the composites was remarkably enhanced with excellent compressive ductility. Superior mechanical properties with the highest strengthening efficiency (65.5%) and tensile strength, acceptable tensile ductility (9.0%) and higher Vickers microhardness were achieved in the 0.15 wt% MLG composites due to its better interface microstructure. The network interface strengthening mechanism by the TiC phase and residue MLG is proposed to be the dominant mechanism with a few contributions from C solid solution and fine-grain strengthening. Unlabelled Image • High-pressure SPS combined with 3D dynamic mixing was used to fabricate graphene reinforced Ti6Al4V composite. • Reaction ratio of TiC to graphene about 7:3 at interface led to better load-bearing capacity. • Composite with 0.15 wt.% graphene addition had the highest strengthening efficiency (65.5%) and acceptable ductility (9%). • The network interface strengthening by the TiC phase and residual graphene was the dominant mechanism. [ABSTRACT FROM AUTHOR]

In order to analyze the strengthen behaviors of the Y element, the microstructures and mechanical properties of Mg-10Gd-0.2Zn- x Y-0.4Zr (x = 0, 1 wt%) two alloys were investigated. Based on the experimental results, Y addition could largely refine the size of β′ precipitate and increase its number density. This phenomenon has been analyzed by theoretical studies in this paper. Due to the fine and dense β′ precipitates, the mechanical properties of the Y-containing alloy was highly improved. In addition, β 1 precipitate also has important contribution to the mechanical property. Based on the TEM observation, after tensile test, the β′ precipitates were obviously sheared by the 11 2 ¯ 0 α slip dislocations in Y-containing and Y-free alloy, then, it illustrates that the strengthen effect in both two alloys was mainly derived from the shearable mechanism. [ABSTRACT FROM AUTHOR]