Solid-solution hardening of bulk crystals

Microhardness H of bulk crystals was investigated by the Vickers pyramid indentation. The H ( x ) curve has a pronounced peak at . In order to investigate a supposed phase separation, samples were annealed at 503 K, 558 K and 621 K for four weeks and at 896 K for one week under suitable partial vapour pressures. In all of them, neither the hardness was essentially altered nor any additional phases, except the solid solution, were found by x-ray analysis and electron diffraction. Nevertheless, the occurrence of nanometer-size clusters of either different structural phases or chemical compositions cannot be excluded.