Thermal transitions in metastable Cu – 68.5 at. % Co alloy.

Arc melted and drop tube processed Cu – 68.5 at. % Co alloy has been subjected to differential thermal analysis (DTA). The liquidus temperature determined from the DTA curves in the arc melt sample (1664 K) was found to be close to phase diagram estimate of 1662 K. In contrast as a result of liquid phase separation in the drop tube samples, the values obtained in the powders were much lower mainly because the compositions of the demixed phases vary from that of the parent melt. The liquidus temperature of the 850 + μm powders was 1632 K while that of the < 38 μm sieve size powder was 1616 K. This variance is due to the asymmetric nature of the metastable phase diagram of the system.

Thermal and Mechanical Properties of Sn-8Zn-3Bi Solder Alloy

Thermal and mechanical properties of Sn-8Zn-3Bi solder alloy on copper substrate were evaluated via measuring the melting temperature, the coefficient of thermal expansion (CTE), the tensile and shear strength of the solder joint. The measured properties of the alloy were then compared to the properties of the traditional and widely used eutectic Sn-37Pb solder alloy. The results show that the melting (liquidus) temperature of Sn-8Zn-3Bi was 195 °C, the CTE of Sn-8Zn-3Bi was 22.2´10-6 K-1 in the temperature range of 30-130 °C. At the same testing condition, both tensile and shear strength of Sn-8Zn-3Bi joints were higher than those of Sn-37Pb. The stress-strain curve indicated that the Sn-8Zn-3Bi joints were brittle whilst the Sn-37Pb joints were ductile.

Effect of phosphorus on the density and molar volume of Al–Si alloy without solidification shrinkage

The Al–Si alloys exhibit many unique properties, but not enough work has been dedicated to their thermophysical properties. In this work, the effect of phosphorus modifier on the density, molar volume and solidification shrinkage rate of Al-25% Si alloys was investigated by using the indirect Archimedes method. The results show that both density–temperature and molar volume–temperature curves show three inflection points: the liquidus temperature point, the eutectic transformation starting point and the finishing point. The density of the solidus linearly decreases and that of the liquidus linearly increases with phosphorus modifier content. Compared with Vegard’s law, the molar volumes show a negative deviation. Finally, the solidification shrinkage rate is calculated from the densities of solidus and liquidus.

Mechanical Properties of CaO–Al2O3–SiO2 Glass-Ceramics Precipitating Hexagonal CaAl2Si2O8 Crystals

Fracture behavior via a flexural test for a newly found CaO–Al2O3–SiO2 (CAS) glass-ceramic (GC) was compared with that of enstatite GC and mica GC, which are well-known GCs with high-fracture toughness and machinability, respectively. By focusing on the nonelastic load–displacement curves, CAS GC was characterized as a less brittle material similar to machinable mica GC, compared with enstatite GC, which showed higher fracture toughness, KIC. The microcrack toughening mechanism in CAS GC was supported by the nondestructive observation of microcracks around the Vickers indentation using the X-ray microcomputed tomography technique. The CAS GC also showed higher transparency than mica GC due to its low crystallinity. Moreover, the precursor glass had easy formability due to its low-liquidus temperature.

Плотность и электросопротивление сплавов Al-Ni-Co-Sm(Tb)

Density and electrical resistivity of Al-Ni-Co-Sm(Tb) glass-forming alloys were studied in wide temperature range include liquid state. It was found the sharp increase of density and decrease of resistivity at liquidus temperature. It was discovered that heating of the melts above a certain temperature leads to the appearance of a hysteresis of properties. Thermal expansion coefficient and temperature coefficient of resistivity were calculated from experimental data.

К 125-летию со дня рождения лауреата Нобелевской премии академика Николая Николаевича Семенова Полуэмпирические методы расчета температур ликвидуса в оксидных системах

In the present study, two semi-empirical methods (geometric and polynomial) were proposed to calculate liquidus temperatures in ternary and quaternary systems using the data on the equilibria in the corresponding binary systems. Advantages, limitations, and peculiarities of application of the semi-empirical methods proposed were considered. The reliability of the results of calculating the liquidus temperature values in the Gd2O3-Y2O3-ZrO2 system was illustrated by comparison with the available data on the phase equilibria. The capacity to evaluate the eutectic line position in the temperature-composition coordinates was shown in multicomponent oxide systems. It was mentioned that the semi-empirical approaches proposed may find a further use to evaluate the liquidus temperature values in multicomponent systems with the aim of reducing the amount of experimental investigations of phase equilibria at high temperatures.