Narrow Results

Structure, Curie temperature, and magnetostriction have been systemically investigated for Tb_0.27Dy_0.73 Fe_1.9+xTi_0.05 compounds using X-ray diffraction, vibrating sample magnetometer, and standard strain gauge technique. The samples show pure MgCu₂-type Laves phase when x≥0.2, and a small amount of second phases appear when x>0.2. The lattice parameters and the Curie temperatures change modestly with increasing Fe content. The magnetostriction of Tb_0.27Dy_0.73Fe_1.9+xTi_0.05 compounds shows strong dependence on Fe content.

A theoretical study of TiX₂ (X = Cr, Mn) with C14 Laves phase compounds has been performed by using the first-principles pseudopotential plane-wave method within the generalized gradient approximation (GGA). The electronic properties (Fermi surface and charge density) have been calculated and analyzed. The optical characteristics (dielectric functions, absorption spectrum, conductivity, energy-loss spectrum and reflectivity) are calculated and discussed. The calculated large positive static dielectric constant indicates good dielectric properties. The reflectivity of TiX₂ (X = Cr, Mn) is high in the IR–Visible–UV region up to $\sim$13 eV showing promise as a good solar heating barrier material. The temperature and pressure dependence of bulk modulus, Debye temperature, specific heats and thermal expansion coefficient are obtained for T = 1200 K and P = 50 GPa through quasi-harmonic Debye model with phononic effects. Fermi surface, optical and thermodynamic properties are very important for practical applications of the materials in optical and other devices.

By using the first-principle calculations, the structural, elastic, electronic and optical properties of Laves phase intermetallic compounds CaRh₂ and LaRh₂ prototype with MgCu₂ are investigated. The evaluated lattice parameters are consistent with the experimental values. The important elastic properties, such as bulk modulus B, shear modulus G, Young’s modulus Y and the Poisson’s ratio v, are computed by applying the Voigt–Reuss–Hill (VRH) approximation. The analysis of Pugh’s ratio exhibits the ductile nature of both the phases. Electronic conductivity is predicted for both the compounds. Most of the contribution comes from Rh-4d states. The study of bonding characteristics reveals the existence of ionic and metallic bonds in both intermetallics. The study of optical properties indicates that CaRh₂ is a better dielectric material than LaRh₂. Absorption quality of both the phases is good in the ultraviolet region.

In current scenario, there is an ever increasing demand for alloys with increased wear resistance under severe working conditions. Ni–Cr–Mo alloy is suitable for surface modification and repairing applications. The Ni–Cr–Mo alloy clad region had cellular-dendrite with Laves phase and complex nitrides/carbides (MX) distributed in the interdendritic regions. Microindentation hardness variation was observed on the interdendritic regions as compared to that of dendritic regions. A new solidification path is confirmed through EDS analysis. Ni, Fe and Cr segregate to the dendritic area, whereas Nb and Mo segregate to the interdendritic region. Ni–Cr–Mo microstructure evolution was studied by optical microscope (OM), scanning electron microscope (SEM) and atomic force microscope (AFM). The Laves and G phases were identified in the Ni–Cr–Mo clad region, confirming superior resistance to corrosion. Pin-on-disc abrasion wear technique confirmed that cladding with low base metal dilution possesses better wear resistance. The mechanism of wear depends on load applied and sliding time. EBSD analysis revealed random texture and grains have same crystallographic orientation across the interface boundary line due to epitaxial growth.