A two-way shape memory alloy, a method of training a shape memory alloy, and a heat engine employing the two-way shape memory alloy to do external work during both heating and cooling phases. The alloy is heated under a first training stress to a temperature which is above the upper operating temperature...http://www.google.co.uk/patents/US4435229?utm_source=gb-gplus-sharePatent US4435229 - Method of preparing a two-way shape memory alloy
