Anneal hardening effect in sintered copper alloys

Samples of copper and copper alloys CuNi and CuNiAl were prepared by a powder metallurgical method and were then subjected to cold rolling with different degrees of deformation. Copper and copper alloys in the cold-rolled state were isochronally annealed up to the recrystallization temperature during which hardness and electrical conductivity were measured. This investigation shows that the anneal hardening effect occurs in a temperature range of 450 - 650 K, followed with an increase in hardness of alloys. Bakar i bakarne legure CuNi i CuNiAl dobijeni su postupkom metalurgije praha a zatim su podvrgnuti hladnom valjanju sa razlicitim ukupnim stepenom deformacije. Bakar i bakarne legure u hladnovaljanom stanju izohrono su zareni sve do temperature rekristalizacije uz merenje tvrdoce i elektricne provodljivosti. Ova ispitivanja su pokazala da je doslo do pojave efekta ojacavanja zarenjem u temperaturnom intervalu od 450 - 650 K, koji je pracen porastom tvrdoce kod legura.