Jinsheng Pan

A new approach to improve the performance of diamond sawblades

Abstract A new kind of matrix containing SiC whiskers for ∅ 105 diamond circular sawblades was developed. Test on the mechanical properties of the matrix and cutting performances of the sawblades indicated that the matrix had appropriate hardness and high bending strength. Sawing test on cutting performance in a stone factory proved that the sawblades made with the new formula had high cutting efficiency and long lifetime during the sawing of granites. The results showed its promising applications.

Wear behavior of TiC–MoSi2 composites

Abstract Titanium carbide (TiC) particles have been added to molybdenum disilicide (MoSi2) to form TiC–MoSi2 composites. Benefits associated with the addition of the TiC to MoSi2 include finer microstructure, higher strength, higher fracture toughness and higher hardness. Under the wear condition of this test, the wear resistance of MoSi2 increases significantly by the addition of TiC particles. The wearing rate of TiC–MoSi2 composites is as low as tenth of monolithic MoSi2. The effects of fracture toughness and hardness on wear resistance are discussed.

TiC whisker-reinforced MoSi2 matrix composites

Abstract A composite of 20 vol.% TiC whiskers in a hot-pressed molybdenum disilicide (MoSi 2 ) matrix was investigated. The microstructure and properties of the composite were characterized. Hot-pressed monolithic material and composite were consolidated to 95.0–95.3% density. No reactions between TiC and MoSi 2 were observed. The composite containing TiC whiskers had higher hardness than monolithic MoSi 2 . The room-temperature flexural strength of the composites increased 120% compared to that of pure MoSi 2 . The room-temperature fracture toughness of the composites was higher than that of MoSi 2 , from 3.2 MPa m 1/2 for MoSi 2 to 5.2 MPa m 1/2 for 20 vol.% TiC w –MoSi 2 . The load-bearing capability and yield strength at elevated temperature for 20 vol.% TiC w –MoSi 2 composite exhibited considerable improvement over that of monolithic MoSi 2 . These results indicated the beneficial effect of TiC whiskers as reinforcements.

A first-principles LMTO-ASA study of crystalline metastable phases in NiNb system

Abstract The phase stability, electronic structure and cohesive properties of metastable crystalline phases Ni 3 Nb and Nb 3 Ni with their cubic L1 2 and hexagonal D0 19 structures have been studied by using the linearized muffin-tin-orbital method with the atomic sphere approximation (LMTO-ASA). The structure preferences are predicted correctly for both the Ni 3 Nb and the Nb 3 Ni metastable phases. Our results show that the calculated equilibrium lattice constants of the metastable phases in NiNb system are in good agreement with the experiment values. The relative stability of different structures are further analyzed in terms of the density of states.

First‐principles calculation of the hexagonal‐closed‐packed Ni75Ta25 metastable phase

The total energy and electronic structure of the hcp Ni76Ta25 metastable phase have been obtained by the self‐consistent discrete variational method and the local Xα exchange approximation. The total energy of this phase was calculated as a function of lattice constant, a, for a fixed c/a of 1.63, which is determined experimentally. The predicted lattice constant, i.e., a=4.93 a.u. is very close to the experimental value of a=4.97 a.u. In addition, the density of states and bonding charge density were used to clarify the characteristics of bonding in this metastable crystalline phase.

A first-principles investigation of the solid-state phase transition in the Mo - Fe system

The first-principles linear-muffin-tin-orbital method has been applied in studying the two-step phase transition induced by ion mixing in Mo - Fe multilayers which has been observed recently. Three different structures, i.e., cubic , hexagonal , and tetragonal , of have been considered in our study. The results are presented in the form of the total energy as a function of the lattice constant, the cohesive properties, and the density of states for the three structures. In agreement with experiment, the structure is found to be more stable than either the or structures, which indicates the possibility of a phase transition from the hexagonal close-packed (hcp) to the face-centred cubic (fcc) form. The predicted lattice constants of these two phases fit very well with the experimental ones. The densities of states are also used to analyse the relative stability of different structures in the Mo - Fe system.

Electronic structure of the hcp Ni-Nb metastable crystalline phase

Abstract The electronic structure of the hcp Ni 75 Nb 25 metastable crystalline phase has been investigated by using the first-principles discrete variational X α method. The total energy curve of this metastable crystalline phase is calculated as a function of the lattice constant using a 19-atom cluster. The predicted equilibrium lattice parameter of this hcp phase agreed well with the experimental value.