THE TERNARY ALLOY SYSTEM: ALUMINIUM–LEAD–SILVER

1. The area of partial miscibility for the ternary system, aluminium–lead–silver, has been determined by thermal and chemical analysis. It is found to extend from the binary system aluminium–lead to alloys containing a maximum of 85.58% silver and 4.71% lead by weight.2. The temperatures of separation of solid phase, bounding this area, have been found to fall at first with addition of silver to the system aluminium–lead, until a temperature of 548.5 °C. is reached. This is the temperature of solidification of the alloy that contains silver and aluminium in their eutectic proportions, plus saturation with lead. The temperature then increases to a maximum of about 736° in the alloy containing about 80% silver and 14% lead. This temperature maximum does not coincide with the summit of the mutual solubility curve but lies well to the right of it.3. No ternary compounds have been found.4. The ternary eutectic practically coincides with the binary eutectic of the system silver–lead.5. As far as can be determined by thermal analysis alone, it appears that there is no solid solution of lead in the α, β, or γ phases of the silver–aluminium system.6. The first peritectic line formed by the addition of lead to the high temperature peritectic point of the silver–aluminium system intersects the partial miscibility curve at 7.90% Al, 7.60% Pb, and 84.50% Ag. The temperature drops from 779.0° to 727.0°.7. The second peritectic line intersects the partial miscibility curve at 10.30% Al, 4.10% Pb, and 85.60% Ag. The temperature drops from 729.0° to 708.0°.8. If the partial miscibility curve had not intervened, the two lines would have intersected at 11.00% Al, 15.50% Pb, and 73.50% Ag.