Considering the coupling of a droplet, keyhole, and molten pool, a three-dimensional transient model for the full penetration laser + metal inert gas (MIG) hybrid welding of thin copper alloy plate was established, which is able to simulate the temperature and velocity fields, keyhole behavior, and generation of the welding defect. Based on the experimental and simulation results, the weld formation mechanism for the hybrid butt welding of a 2 mm-thick copper alloy plate was comparatively studied in terms of the fluid dynamic feature of the melt pool. For single laser welding, the dynamic behavior of liquid metal near the rear keyhole wall is complex, and the keyhole has a relatively drastic fluctuation. An obvious spattering phenomenon occurs at the workpiece backside. Meanwhile, the underfill (or undercut) defect is formed at both the top and bottom surfaces of the final weld bead, and the recoil pressure is identified as the main factor. In hybrid welding, a downward fluid flow is strengthened on the rear keyhole wall, and the stability of the keyhole root is enhanced greatly. There are large and small clockwise vortexes emerging in the upper and lower parts of the molten pool, respectively. A relatively stable metal bulge can be produced at the weld pool backside. The formation defects are suppressed effectively, increasing the reliability of full penetration butt welding of the thin copper alloy plate.

Wire + Arc Additive Manufacturing (WAAM) is an advanced manufacturing technology by inexpensive Gas Tungsten Arc Welding (GTAW) technology. Key microstructural features of the as-built WAAM alloy include large columnar ¢ grains, grain boundary ¡ colonies, and Heat Affected Zone (HAZ) banding, which generally leads to low ductility and anisotropy. In this study, Ti6AlxV (x = 0, 2, 4) alloys were prepared by WAAM, the effects of vanadium content on the microstructure, tensile properties and impact toughness were investigated. Irregularshaped, plate-like features without columnar grains and HAZ banding were obtained in Ti6Al alloy. Columnar grains were observed in Ti6Al 2V alloy, and the grain size was further enlarged to more than ten millimeters by 4 mass% vanadium addition. With the increasing of vanadium content, a monotonic increase in yield strength and ultimate tensile strength can be observed, while the fracture strain and impact toughness changed in the opposite trend. Ti6Al and Ti6Al2V alloy exhibited better matching of strength, ductility and impact toughness compared with Ti6Al4V alloy.

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Metal matrix composites [MMC] are most important materials used for recent works in the industry and engineering applications. Fly ash particles are used in metal matrix composites, are low costand low density are available in large quantities of waste by product in power plants. The adding of fly ash with aluminium reinforcement by using stir casting process it can reduces the cost and density of aluminium material. Metal composite processes are improved mechanical properties like strength, hardness, low density and good wear resistance compared to other metals. In this study,aluminium clad and fly ash chemical analysis is studied before and after mixing and forming as particulate metal matrix composite and comparing the mechanical, physical properties of the MMC at varying % of fly ash addition. By comparison at various levels 15% of fly ash the MMC gives good mechanical and physical properties. This type of MMC is widely useful in light weight vehicles and aerospace application.

First-principles calculations were used to investigate the stability, electronic structure, elastic and lattice thermal conductivity of FeS and FeS2 polymorphs ([Formula: see text]-FeS, [Formula: see text]-FeS, [Formula: see text]-FeS, [Formula: see text]-FeS2, [Formula: see text]-FeS2). The calculated lattice parameters were in agreement with experimental results. The results showed that these Fe-S binary compounds are thermodynamically and mechanically stable. The elastic anisotropies of Fe-S binary compounds were exhibited by 3D modulus ball and 2D projections. Among all the five compounds, [Formula: see text]-FeS2 compound has the largest bulk modulus and [Formula: see text]-FeS2 has the largest Young’s modulus and hardness. Furthermore, [Formula: see text]-FeS, [Formula: see text]-FeS and [Formula: see text]-FeS compounds can be regarded as ductile material according to [Formula: see text] and Poisson’s ratio. The FeS compounds show metallic character and FeS2 compounds show semiconductor character through analyzing their bandgap and density of states (DOS). The [Formula: see text]-FeS2 has the largest thermal conductivity according to the Clarke model, and the [Formula: see text]-FeS shows the strongest thermal conductivity anisotropy among the five compounds.