In this study, oxide (Y2O3)-embedded Ni particles were fabricated via a new process. The process involves the mechanical hydrogenation of Ni–Y alloy into Ni–YH2 and the selective oxidation of Ni–YH2 to Ni–Y2O3. The alloy powders were prepared for sintering by the mechanical alloying of a mixed powder. The powder was prepared with a desired composition (Ni–20wt.%Cr–1.2wt.%Y2O3) by adding Ni and Cr powders to the Ni–Y2O3 composite prepared by the new process. For comparison, a mixed powder with the same composite was prepared using a conventional mechanical alloying (MA) approach. Samples of the two powders were sintered by SPS at 850, 900, 950, and 1,000 ^oC. The relative densities of all samples were higher than 99.7% at all sintering temperatures. The oxide particles and matrix grain sizes of the Ni–20Cr–1.2Y2O3 alloy prepared by this new process were finer than those in alloys fabricated by conventional MA processes. Therefore, the improvement in the mechanical properties of the Ni–20Cr–1.2Y2O3 alloy prepared by the new process was attributed to the refinement of the oxide particles.

In this study, oxide (Y2O3)-embedded Ni particles were fabricated via a new process. The process involves the mechanical hydrogenation of Ni–Y alloy into Ni–YH2 and the selective oxidation of Ni–YH2 to Ni–Y2O3. The alloy powders were prepared for sintering by the mechanical alloying of a mixed powder. The powder was prepared with a desired composition (Ni–20wt.%Cr–1.2wt.%Y2O3) by adding Ni and Cr powders to the Ni–Y2O3 composite prepared by the new process. For comparison, a mixed powder with the same composite was prepared using a conventional mechanical alloying (MA) approach. Samples of the two powders were sintered by SPS at 850, 900, 950, and 1,000 ^oC. The relative densities of all samples were higher than 99.7% at all sintering temperatures. The oxide particles and matrix grain sizes of the Ni–20Cr–1.2Y2O3 alloy prepared by this new process were finer than those in alloys fabricated by conventional MA processes. Therefore, the improvement in the mechanical properties of the Ni–20Cr–1.2Y2O3 alloy prepared by the new process was attributed to the refinement of the oxide particles.

The effect of plasma-radical change on the surface properties of Zn-Mg-Al ternary-alloy-coated steel sheets during atmospheric-pressure (AP) plasma treatment using different process gases: O 2, N 2, and compressed air was investigated. The plasma-induced radicals promoted the formation of chemical particles on the surface of the Zn-Mg-Al coating, thereby increasing the surface roughness. The surface energy was calculated using the Owen-Wendtgeometric equation. Contact angle measurements indicated that the surface free energy of the alloy sheets increased upon AP plasma treatment. The surface properties of the Zn-Mg-Al coating changed more significantly in the order air > O 2 > N 2 gas, indicating that the plasma radicals facilitated the carbonization and hydroxylation of the Mg and Al components during the AP plasma treatment.

Structural-adhesive-assisted DeltaSpot welding was used to improve the weldability and mechanical properties of dissimilar joints between 6061 aluminum alloy and galvannealed HSLA steel. Evaluation of the spot-weld-bonded surfaces from lap shear tests after long-term exposure to chloride and a humid atmosphere (5% NaCl, 35 °C) indicated that the long-term mechanical reliability of the dissimilar weld in a corrosive environment depends strongly on the adhesive-Al6061 alloy bond strength. Corrosive electrolyte infiltrated the epoxy-based adhesive/Al alloy interface, disrupting the chemical interactions and decreasing the adhesion via anodic undercutting of the Al alloy. Due to localized electrochemical galvanic reactions, the surrounding nugget matrix suffered accelerated anodic dissolution, resulting in an Al6061-T6 alloy plate with degraded adhesive strength and mechanical properties. KrF excimer laser irradiation of the Al alloy before adhesive bonding removed the weakly bonded native oxidic overlayers and altered the substrate topography. This afforded a low electrolyte permeability and prevented adhesive delamination, thereby enhancing the long-term stability of the chemical interactions between the adhesive and Al alloy substrate. The results demonstrate the application of excimer laser irradiation as a simple and environmentally friendly processing technology for robust adhesion and reliable bonding between 6061 aluminum alloy and galvannealed steel.