The effect of cryogenic treatment on ageing behaviour of B4C reinforced 7075 aluminium composite

In the current study, an effect of cryogenic treatment on the ageing of a B4C particulate reinforced 7075 aluminium alloy was investigated to identify changes in hardness with respect to ageing time. To achieve this, first, 10, 15, and 25 \% by weight B4C particulate containing 7075 Al composite specimens were produced by hot pressing of Al, Cu, Zn, and Mg elemental powders. Next, cryogenic treatment and multiple steps of tempering were adapted to several samples. Such as, after solutionizing at 470 degrees C and sub-zero treatment at -146 degrees C, successive intervals of artificial ageing at 120 degrees C for different time periods were applied. During the heat treatment, hardness values were measured after each interval. Findings reveal that, particularly after solutionization, cryogenic treatment before ageing yields high hardness values. However, the hardness of the composite material exceeds this level during ageing treatment, mainly after long ageing times