Wenyan Zhai

Cr3C2–20%Ni cermets prepared by high energy milling and reactive sintering, and their mechanical properties

Cr3C2–20%Ni cermets were fabricated with Cr, C and Ni mixed-powder by high energy milling and reactive carburising sintering. The elemental powders of Cr, C and Ni were mixed with proper ratio (Cr/C = 3:2 atomic ratio) and milled to the nanometre crystallite sizes (about 20–30 nm). Specimens were cold-isostatically pressed at 200 MPa and sintered at 1453, 1503 and 1553 K with vacuum atmosphere for 1 h, respectively. It was shown that the relative density of the sintered specimens increases first and then decreases slightly with increasing sintering temperature. The maximum values of the hardness (86.7HRA) and bending strength (1140 MPa) were achieved at 1503 K.

Pressure Prediction of Electronic, Anisotropic Elastic, Optical, and Thermal Properties of Quaternary (M2/3Ti1/3)3AlC2 (M = Cr, Mo, and Ti)

The electronic, mechanical, anisotropic elastic, optical, and thermal properties of quaternary (M2/3Ti1/3)3AlC2 (M = Cr, Mo, and Ti) under different pressure are systematically investigated by first-principles calculations. The bonding characteristics of these compounds are the mixture of metallic and covalent bonds. With an increase of pressure, the heights of total density of states (TDOS) for these compounds decrease at Fermi level. The highest volume compressibility among three compounds is Mo2TiAlC2 for its smallest relative volume decline. The relative bond lengths are decreasing when the pressure increases. The bulk and shear modulus of the one doped with Cr or Mo are larger than those of Ti3AlC2 with pressure increasing. With an increase of pressure, the anisotropy of these compounds also increases. Moreover, Mo2TiAlC2 has the biggest anisotropy among the three compounds. The results of optical functions indicate that the reflectivity of the three compounds is high in visible-ultraviolet region up to ~10.5 eV under ambient pressure and increasing constantly when under pressure. Mo2TiAlC2 has the highest loss function. The calculated sound velocity and Debye temperature show that they all increase with pressure. of the three compounds is also calculated.

Effect of molybdenum addition on the microstructure and mechanical properties of Cr3C2-20 wt. % Ni cermet

Abstract Effect of Mo addition on the microstructure and mechanical properties of Cr3C2-20 wt. % Ni cermet was investigated. Three different phases can be seen in the microstructure after adding appropriate molybdenum. The completely undissolved (Cr, Mo)3C2 phase maintains the original grain size and effectively prevents the (Cr, Mo)7C3 grains from merging and growing. The relative densities of the sintered specimens decrease slightly, while the hardness and bending strength increase firstly and then decrease slightly with the increase of Mo content. The maximum values of the hardness (88·6 HRA) and bending strength (1200 MPa) are achieved with 1 wt. % Mo addition.