The mechanical properties and internal friction (damping capacity) of Mg–Zn–Y alloys with a long-period stacking ordered (LPSO) structure at different Y/Zn atomic ratios (2/1, 3/2 or 4/3) in cast and extrusion were investigated. It was found that the as-cast Mg–Zn–Y alloys with different Y/Zn atomic ratios possess a single LPSO phase with the same stable 18R-type structure. Among the three alloys, the alloy with 3/2 atomic ratio yields the highest damping capacity in low- and high-strain amplitude stages. Two damping peaks particularly P1 and P2 are detected in the Mg–Zn–Y alloy with 3/2 atomic ratio at approximately 108 and 220 °C, respectively. These results may be attributed to few solute atoms in Mg matrix and grain boundaries. In addition, the studied alloy with 3/2 atomic ratio exhibits excellent comprehensive properties in as-cast and as-extruded states; this alloy yields an ultimate tensile strength of 346 MPa and maintains a certain damping capacity (Q−1 > 0.01) in extrusion.

In this study, the precipitation behavior of the pretwinned extruded Mg–6Al–1Zn alloy was investigated. It was observed that the precipitates preferentially nucleated at the twin boundaries or within the preexistent twins. This distribution of the precipitates led to the distinguishing influences on subsequent compression and tension process, which were dominated by twinning and detwinning of the preexistent twins, respectively. The compressive yield strength after aging was a little lower than the stress when the precompression was interrupted, which meant that the impeding effect of precipitation on twin expansion was relatively smaller than that of dislocations induced by precompression. However, the tensile yield strength of aged samples was extremely higher than that of non-aged samples as the migration of the twin boundaries during detwinning was considerably hindered because of the preferential precipitation within the preexistent {10-12} twins.

The microstructures of the cast Mg–3Al–1Zn–xCe (x = 0, 0.2, 0.4, 0.8, and 1.2 wt%) alloys produced by twin-roll casting were observed to reveal the effect of cerium (Ce) on the Mg–3Al–1Zn (AZ31) alloy. Transmission electron microscopy (TEM) image of Al4Ce particles at the centers of grains was observed, and the crystallographic calculations between Al4Ce and α-Mg were examined on the basis of the edge-to-edge matching model. The results indicated that the addition of Ce effectively reduces the grain size of the cast AZ31 alloy produced by twin-roll casting. The finest grains with an average grain size of 55 μm are achieved at 0.4 wt% addition of Ce. TEM observation and good crystallographic matching between Al4Ce and α-Mg suggest that promotion of heterogeneous nucleation of α-Mg on Al4Ce particles formed in the melt is responsible for the grain refinement when adding Ce to the cast AZ31 alloy.

The microstructure evolution and mechanical responses are investigated in uniaxial tensile test performed on AZ31 magnesium alloy sheets processed by the flat extrusion container. A novel emphasis based on the texture was used to estimate the relative magnitude of hardening effects related to the deformation twinning. The anisotropic behavior of the sheets is sensitive to the orientation of the crystals with respect to the loading direction. This is ascribed to the effect of the initial texture and the activation of their relative critical resolved shear stresses on slip and twinning. The increased accumulated hardening increases the twin nucleation stress. The deformation twinning significantly induces an asymmetry in the yield behavior. Moreover, it remarkably prolongs the slope of the stage II in the working hardening curve. An accepted notion is proposed that the preferential activity of deformation twinning exerts a significant effect on mechanical anisotropy during tension.

Mg-Li-Al alloy was prepared by ingot casting and then underwent subsequent reactive ball milling. A Mg-Li-Al-H complex hydride was obtained under a 0.4 MPa hydrogen atmosphere at room temperature, and as high as 10.7 wt% hydrogen storage capacity was achieved, with the peak desorption temperature of the initial step at approximately 65 °C. The evolution of the reaction during milling, as well as the effect of Li/Al ratio in the raw materials on the desorption properties of the hydrides formed, were studied by x-ray diffraction and simultaneous thermogravimetry and differential scanning calorimetry techniques. The results showed that mechanical milling increases the solubility of Li in Mg, leading to the transformation of bcc β(Li) solid solution to hcp α(Mg) solid solution, the latter continues to incorporate Li and Al, which stimulates the formation of Mg-Li-Al-H hydride. A lower Li/Al ratio resulted in faster hydrogen desorption rate and a greater amount of hydrogen released at a low temperature range, but sacrificing total hydrogen storage capacity.

Mg2Ni1-xCux (x = 0, 0.2, 0.4) and Mg2Ni1-yCoy (y = 0, 0.2, 0.4) were successfully synthesized via two steps: induction melting and then ball milling. The component and microstructure of the alloys were determined with x-ray diffraction (XRD) and scanning electron microscopy/x-ray energy-dispersive spectrometry (SEM/XEDS). Mg2Ni phase was observed in all 5 alloys. When the amount of Cu was increased, it led to the formation of phase from Mg2Cu to Cu11Mg10Ni9. Co2Mg was detected in the Co-containing alloys. The hydrogen absorption/desorption properties were tested with p-C-T measurement apparatus, and the results showed that the gaseous storage properties of the alloys were improved by the addition of Cu or Co.

The mechanism of reactive wetting of metal/ceramic was investigated on the basis of a detailed description of the thermodynamics of interfacial reactions. The interfacial reaction of the metal/ceramic system has been treated as the reaction between the surface phase of the metal matrix and that of the substrate. It is concluded that reactive wetting is governed not only by the term accounting for the intensity of interfacial chemical reactions but also by the term accounting for the physicochemical properties of the resulting interface. In some cases, only one of them contributes dominantly to wetting. The criteria for the choice of an alloying element to promote wetting should not only include its reactivity with the substrate but also its ability to favorably modify the metal/substrate interface.