Indentation creep behavior of AE42 and Ca-containing AE41 alloys

The indentation creep behavior of AE42 and 0.4–1.2 wt.% Ca-containing AE41 alloys was studied. The microstructure was analyzed by an optical microscope, XRD and SEM equipped EDS before and after indentation creep. The results indicate that the creep resistance of AE41 alloys is improved with the addition of Ca. The indentation creep resistance of Ca-containing AE41 alloys is better than that of AE42 at 150 °C and 175 °C. The microstructure analysis shows that the Al₁₁Nd₃ phase in AE42 is prone to decompose above 150 °C, which deteriorates its creep resistance behavior. Ca-containing AE41 alloys have good indentation creep resistance because of the formation of heat-resistant phase Al₂Ca in the alloys.     

Analysis of a two-dimensional invariant line interface for the case of a general transformation strain and application to thin-film interfaces

An explicit solution is obtained for a general two-dimensional deformation matrix between two phases containing any combination of expansion/contraction and/or shear. Application of the solution to various cases of deformation shows that in the presence of a shear, an invariant line can be obtained even when the deformations along orthogonal directions are both contractions or expansions. Utilization of the solution in the design of thin-film overgrowths on substrates and the relationship between the solution eigenvectors in real and reciprocal space are discussed.     

Preparation of MgH2 composite with a composition of 40%MgH2 + 30%LiBH4 + 30%(2LiBH4 + MgF2)

A mixture of containing two chemical equivalents of lithium borohyride and one equivalent of magnesium fluoride is known to yield hydrogen in an amount of about 7.6 wt% of the mixture when heated to about 150 °C at atmospheric pressure by the following reaction; 2LiBH₄ + MgF₂ = 2LiF + MgB₂ + 4H₂. In order to increase hydrogen storage capacity of Mg-based materials, a mixture with a composition of 2LiBH₄ + MgF₂ and LiBH₄with a higher hydrogen storage capacity of 18.4 wt% were added to MgH₂. MgH₂ composite with a composition of 40 wt%MgH₂ + 30 wt%LiBH₄ + 30 wt%(2LiBH₄ + MgF₂) was prepared by reactive mechanical grinding. The hydrogen storage properties of the sample were then examined. Hydrogen content vs. desorption time curves for consecutive 1st desorptions of 40 wt%MgH₂ + 30 wt%LiBH₄ + 30 wt%(2LiBH₄ + MgF₂) at 533–873 K showed that the total desorbed hydrogen quantity for consecutive 1st desorptions is 7.07 wt%.     

镁基材料摩擦磨损的研究进展

主要综述了近年来镁基材料(包括镁合金和镁基复合材料)摩擦磨损的研究状况,总结了合金元素对摩擦磨损的影响,对比分析了触变成形、压铸和金属型铸造镁合金的摩擦磨损,研究了各种镁基复合材料的摩擦磨损,同时总结了表面改性对镁基材料摩擦磨损的影响.     

Damping properties in Mg–Zn–Y alloy with dispersion of quasicrystal phase particle

The effect of the interface structure between the matrix and the particle on the damping capacity was investigated using Mg–Zn and Mg–Zn–Y alloys in this study. The damping capacity was not affected by the interface structure at room temperature. However, the onset of temperature, which was higher in the Mg–Zn–Y alloy than in the Mg–Zn alloy despite their similar grain sizes, increased the damping capacity through grain boundary relaxation by grain boundary sliding. Compared to the Mg–Zn alloy, the existence of the quasicrystal phase particles, which had the coherent interface with low interface energy, was likely to have suppressed and delayed the grain boundary sliding in the Mg–Zn alloy.     

Magnetic Domain Structure: Analysis of Magnetic Reversal in RE-3d Permanent Magnets

The possibilities of direct magnetic domain observation on surfaces of modern permanent magnets SmCo₅, Sm-Zr-Co-Cu-Fe, Nd-Fe-B by means of the magneto-optical Kerr effect for the quantitative and qualitative testing of magnetization and magnetic reversal processes and nature of magnetic hysteresis were analyzed. For all types of investigated magnets, the angular dependences for saturation field H_S, critical field of reverse domain removal H_K, and nucleation field H_n of individual grains were found to obey the law 1/cosϕ, where ϕ is the angle between the grain easy axis and external magnetic field.