Zeng Song-yan

First-principles study on the elastic properties of platinum nitride

Elastic properties of platinum nitride (PtN) are studied by first-principles calculations with the fully relativistic full potential linearized augmented plane-wave (LAPW) method, the plane-wave ultrasoft pseudopotential (PW-PP) and the projector-augmented wave (PAW) methods. The results reveal that: (1) the scalar relativistic scheme is sufficient to treat the valence electronic structure, i.e. the spin-orbit effect has little effect on the bulk modulus value of platinum nitride; (2) the all-electron full potential method is no more accurate than the pseudopotential and PAW-based methods when calculating the lattice constant and bulk modulus properties of the platinum nitride; (3) platinum nitride in zinc-blende structure is unstable and its crystal structure is still an open problem.

Microstructure of XDTM Ti-6Al/TiC composites

XDTM method has been used to prepare TiC particles reinforced titanium composites. The phases constitute and microstructure of the Ti-6Al/TiC composites have been investigated by XRD and SEM. The lattice parameter value of TiC calculated from the XRD pattern has indicated that there exists carbon deficiency in TiC. The microstructure observed by SEM has shown that TiC is of dendritical and spherical morphology, which quite different from that of the TiC in Al/TiC master alloy. In macrostructure, the TiC particles homogeneously distribute in the matrix, but the spherical TiC mainly segregate at the grain boundary, especially at the triangle grain boundary. Microstructure of the interface has also been observed by TEM and HTEM. No reaction product has been found in the interface, but a C atom diffusion layer was determined by energy spectrum diffraction and observed by HREM image of interface microstructure. Although no definite crystallographic relationship can be defined, a orientation relationship of [01―10]Ti//[011]TiC has been obtained.

Structure and microhardness of rapidly solidified AlCrRE (RE ≡ La-rich misch metal) alloy

Abstract In the work reported in this paper, rapidly solidified thin ribbons with compositions of Al(4–10 wt.%)Cr4wt.%RE (RE denotes La-rich misch metal) were produced by a single-roller technique. Phase formation and microstructures of the alloys were studied by X-ray diffraction, transmission electron microscopy, electron probe and energy spectrum analysis. Microhardnesses of the alloys were measured with a microhardness meter. The results show that the alloy Al(4–6 wt.%)Cr4wt.%RE is a promising materials for elevated temperture uses.