SHAPE-MEMORY ALLOYS

This article describes in detail the mechanism by which certain alloys exhibit shape memory effects, and the conditions involved in which these effects can be attained. The main aplications for both nickel-titanium alloys and ternary (copper, zinc and aluminium) alloys are described. These include couplings for pneumatic and hydraulic lines, seals and couplings in electronic assemblies, use in artificial human joints, and in the repair of fractured limbs, and thermostatic valves. Another suggested use is in the form of a shape memory engine to utilize the thermal energy of a large body of water for example an ocean or reservoir. (C.T.)