Order hardening in platinum 14 at.% copper

Platinum 14 at.% copper is shown to harden after heat treatments which result in an ordering transformation. Specimens were first disordered by quenching from high temperature or by cold work. Subsequent heat treatment at temperatures between 100 °C and 400 °C resulted in the formation of small ordered domains of CuPt7 in a disordered matrix, accompanied by an increase in hardness. Prior cold work is shown to result in significant hardening after heat treatment, whereas prior quenching results in a smaller increase in hardness.