Abstract: Differences in thermal expansion properties between integrated circuit chips, especially of gallium arsenide, and the dielectric substrates (especially diamond and aluminum nitride) on which said chips are mounted are accommodating by interposing between the substrate and the chip a mixed metal layer comprising at least one ductile, thermally conductive metal such as copper and at least one other metal, preferably a refractory metal, having a lower coefficient of thermal expansion, preferably tungsten. A compliant metal layer, typically of aluminum, silver, copper or gold, is preferably interposed between the substrate and the mixed metal layer.

Abstract: Divalent titanium is prepared by the reduction of higher valence titanium halides in a molten salt electrolyte for subsequent titanium deposition with aluminum to form alloys exhibiting excellent mechanical properties for use at high temperatures. At least one aluminum halide such as AlCl.sub.3 is combined with aluminum metal, at least one titanium halide such as TiCl.sub.3 where the titanium has a valence greater than two, and at least one salt capable of forming a melt with said aluminum halide at temperatures up to about 250.degree. C. to form a molten salt electrolyte. The salt may be an alkali, alkaline earth or organic halide. Upon heating in an inert atmosphere at a temperature greater than the melting point of the electrolyte, the higher valence titanium is reduced by aluminum metal to form divalent titanium. Titanium-aluminum alloys of up to 50 atomic percent titanium can then be deposited from the electrolyte.