Characteristics and Microstructure of 7055 Al Alloy Powder Prepared by Nitrogen Atomization

The defects, particle size, microstructure, solidification rate and thermal stability of nitrogen atomized 7055 Al alloy powder were systematically studied. The results show that the alloy powder exhibits a network-like fine dendrite structure, the solidification rate of most powder is between 3 x 104 and 5 x 105 K s-1, and the main phases are alpha-Al and MgZn2. The alloy powder can still maintain fine dendritic structure with rapid solidification characteristics after holding at 400 celcius for 1 h, while the metastable non-equilibrium structure transformation occurs when holding above 400 celcius and this means that the fine dendritic structure is consolidated and coarsened.