Dependence of mechanical properties of binary platinum-rhodium alloys on valence electron ratio (VER), number of valence electrons (e_v) and average atomic number of the alloys (Z) are investigated. The alloys have a high number of valence electrons (9 ≤ e_v ≤ 10) and a wide range of average atomic numbers (Z = 45–78). Clear correlations between VER of the alloys and their mechanical properties are found. By increasing the VER of the alloy from 0.13 to 0.20 following the increase of rhodium content in the composition, the hardness, elastic modulus and ultimate tensile strength (UTS) of the alloy increases. Creep rates of the selected alloys clearly decrease with increasing VER at high temperatures (1500–1700°C), while stress rupture time at different temperatures consistently increases because of higher rhodium content in the alloy solid solution chemistry. Dependence of mechanical properties on valence electron parameters is discussed with reference to the atomic bonding.

Definitive equations are suggested to represent the variation with temperature of the densities and molar volumes of the liquid platinum group metals whilst the previously unknown initial slopes of the melting curves for iridium, rhodium and ruthenium are estimated. 1. Introduction Paradis et al. (1) summarised determinations of the densities of the liquid platinum group metals but a...

Ruthenium targets were prepared by vacuum hot pressing of ruthenium powder with different morphologies. Ruthenium films were then deposited on a SiO₂/Si(100) substrate for different times by radio frequency (RF) magnetron sputtering. The relationship in terms of the microstructure and electrical properties between the ruthenium targets and resultant films at different conditions were studied by means of field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and four-point probe. The results showed that parameters such as the average deposition rate, surface roughness, crystallisation properties and growth rate were directly related to the homogeneity of the microstructure of the ruthenium targets, but there was no correlation between the crystal orientations of the films and the targets. Moreover, the resistivity of ruthenium films was positively correlated with that of the ruthenium targets.