Microstructure and mechanical properties of 7055 Al alloy prepared under different sintering conditions using powder by-products

To efficiently reuse the powder by-products produced during the production of the spray-formed 7055 alloy, a 7055 aluminum alloy was prepared by traditional powder metallurgy by using powder by-products as the raw materials. In addition, characteristics of the powder by-products and effects of the sintering conditions on the microstructure and properties of the 7055 Al alloy are investigated. The densification mechanism of the powder by-products during sintering is revealed. The results indicated that the existence of an oxide layer on the particle surface of the powder by-product as well as pores inside the particles. The shrinkage and densification of the sintered body during vacuum sintering is hindered by the oxide layer, and lead to a low relative density and strength. However, the shrinkage and the densification of sintered body are promoting by the fracture of oxide layer under the pressure during hot-press sintering, and result in a high relative density and strength. At a temperature of 550 degrees C, a pressure of 12 MPa, and a holding time of 120 min, the as-sintered 7055 alloy with the relative density of 99.70% and the ultimate tensile strength of 277.72 MPa are obtained.

Automated summary

7055 aluminum alloy was prepared using powder by-products, with studies showing that the oxide layer affects the density and strength of the sintered body. However, fracture of the oxide layer during hot-press sintering can improve the density and strength of the sintered body.