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The effect of alloying on the formation enthalpy of TiCu intermetallics was investigated via first-principles calculations to propose a new design method for Ti–Cu-system metallic glasses. The calculation results showed good agreement with the reported experimental results that Ni, Pd, Sn and Zr improve this system’s glass-forming ability. According to the calculation results, a Ti–Zr–Cu–Ga system was designed as a potential new bulk Ti-based metallic glass, and a bulk sample with a 2-mm diameter was fabricated.

Enthalpies of solutions and misfit strains for the Al–X (X = H, B, C, N, and O) binary alloys were determined by first-principles calculations to estimate the strengthening of solid solutions caused by interstitial atoms. The results indicate that interstitial solute atoms produced large misfit strains. Electrodeposited Al containing 0.12–1.32 at.% C was used to assess the validity of solid-solution strengthening by interstitial solute atoms. The role that interstitial carbon plays in strengthening electrodeposited Al is discussed.

To gain insight into accommodation mechanisms for local stress concentrations produced by grain boundary sliding (GBS), we systematically examined texture evolution within a superplastic magnesium alloy undergoing deformation at a relatively low deformation temperature (at which basal slip is known to be the preferred slip system in magnesium). Although we did observe an overall weakening of the initial basal texture during superplastic deformation, we also observed within the interior of the specimen a convergent evolution that depends on loading direction. We attribute this texture evolution within the bulk to the competing effects of (a) orientation divergence due to grain rotation accompanied by GBS and (b) convergent evolution due to slip, which acts primarily as an accommodation mechanism for GBS. In contrast, at the near-surface, we found the initial orientation to be preserved, indicating that slip accommodation is less important near the surface than within the bulk.

The effect of alloying elements on the threshold stress for superplasticity was investigated using two binary solid solutions, namely, Mg–Al and Mg–Y alloys. Both alloys exhibited superplasticity, and in spite of the absence of fine particles showed threshold-stress-like behavior. Different origins were suggested for the threshold-stress-like behavior after considering grain growth during deformation. The threshold-stress-like behavior in Mg–Al alloys originates from the effects of microstructural instability (grain-growth hardening). On the other hand, analysis of grain-boundary segregation suggested that the threshold-stress-like behavior in Mg–Y alloy originates from the segregation of yttrium in grain boundaries and its interaction with grain-boundary dislocations.

Grain boundary relaxation at elevated temperatures in fine-grained pure magnesium and Mg–Al solid solutions was investigated by measuring damping capacity at low frequencies. A sharp increase in damping capacity caused by grain boundary relaxation was observed at above a certain temperature. The onset temperature depended on aluminum content; the onset temperature increased with aluminum content. It was demonstrated that aluminum was effective in suppressing grain boundary relaxation in magnesium alloys. However, additional measurement of the damping capacity of a dilute Mg–Y alloy revealed that yttrium was more effective in suppressing grain boundary relaxation.