S. P. Sen Gupta

An X-ray determination of the thermal expansion of α-phase Ag–Ga alloys at high temperatures

The lattice parameters of four Ag-Ga alloys in the solid-solution range have been determined by X-ray methods in the temperature interval of 26-522°C using a Unicam 19 cm high-temperature powder camera. In all the cases the lattice parameters have been found to increase in a non-linear manner in the measured range of temperature and the relationship has been expressed in analytical form from the least-squares fitting of data. The linear thermal expansion coefficients have, however, been found to decrease with increasing temperature.

X-ray measurements of stacking faults in copper–antimony alloys

The line profiles from cold-worked copper-base alloys containing pentavalent solute antimony in the primary solid solution range have been recorded by a Geiger counter X-ray diffractometer. The deformation fault probability α and the twin fault probability β have been obtained from peak shift and peak asymmetry measurements respectively. A roughly parabolic variation of α with increasing solute content has been observed. However, the increase of α with the increase of solute valency for fixed electron concentration per atom is not clearly established. The twin fault probability βalso increases in a similar way as observed in other copper-base alloys.

An X-ray determination of the thermal expansion of silver and copper-base alloys at higher temperatures. III. Ag–Ge and Cu–Ge

X-ray measurements of the lattice spacings in three Ag-Ge alloys in the temperature interval 30-595°C and in two Cu-Ge alloys in the temperature interval 25-611°C, in the solid-solution range, have been made with a Unicam 19 cm high-temperature camera. The measured lattice spacings have been found to increase non-linearly with temperature, this non-linearity being slightly enhanced for Cu-9.25 at.% Ge alloy. The dependence of the measured lattice spacings on temperature has been expressed in an analytical form (polynomial of second degree) from least-squares fitting of the data. The thermal expansion coefficient, α, for the alloys considered, in general, has been found to decrease linearly with increasing temperature (from ∼25 to ∼17 × 10-6°C-1), except for the greater germanium concentration (9.25 at.%) in copper solvent where the tendency is reversed.

An X-ray determination of the thermal expansion of silver and copper-base alloys at high temperature. II. Cu–Ga

X-ray measurements of the lattice parameters have been made in four Cu-Ga alloys in the solid-solution range using a Unicam 19 cm high-temperature camera in the temperature interval of 30-514 °C. The measured lattice parameters have been found to increase non-linearly with the temperature and this variation has been expressed in an analytical form from least-squares fitting. The linear thermal expansion coefficients have been found to decrease with increasing temperature in these alloys with a tendency to attain a nearly constant value at higher solute concentrations, and the decrease is rather slow compared to that observed earlier with Ag-Ga alloys over the same range of temperature.