Ageing Hardning and Precipitationg of the 7A60 Alloy during Cooling Aging

Abstract

Effect of non-isothermal aging treatment on microstructure and properties of 7A60 aluminum alloys was in present work. Hardness is decided by the start cooling temperature and cooling rate, high initial cooling temperature and fast cooling rate will improve the hardness of the alloy. The electrical conductivity of the alloy is mainly determined by the initial temperature, the higher the initial temperature, the higher the conductivity. Hardness and electronic conductivity were improved greatly during initial cooling stage. Afterward, hardness and conductivity was slightly affected. Transmission electron microscopy (TEM) and high-resolution transmission electron microscope (HRTEM) analysis showed that the main strengthen precipitate of the 7A60 alloy by cooling aging is plate-like eta' phase, which precipitating along the {111}Al. There are great different in the size of eta' phase, which dispersed in Al grains, and the PFZ is narrow by high temperature rapid cooling aging.