On the Effect of the Oxidative Milling of Matrix Powder on the Structure and Properties of Aluminum Foam Based on the Al–12Si Alloy

The effect produced by the time of milling the aluminum Al–12Si alloy powder in a ball mill in an air atmosphere on the macrostructural characteristics of aluminum foam was studied. The milling time was from 5 to 20 min at a speed of 300 rpm and a ball to powder mass ratio of 8 : 1. The treated matrix alloy powder was mixed with 1 wt % of TiH 2 , thereupon compact cylindrical specimens were manufactured by hot pressing at a temperature of 400°C. The foaming of specimens was performed in steel die at a temperature of 800°C. The results demonstrated that an increase in the time of milling the powder of aluminum matrix alloy to 15 min had a positive effect on the process of foaming due to a growth in the oxidation level as exhibited by a decrease in the size of formed pores and the density of aluminum foam specimens. However, a further increase in the milling time, at which powder particles coarsened as a result of cold welding, led to the degradation of the macrostructural characteristics of a foam specimen.