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

Abstract

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• C and sub-zero treatment at -146• C, successive intervals of artificial ageing at 120• 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.K e y w o r d s:

Effect of deep sub-zero treatment on mechanical properties of AA5XXX aluminum plates adjoined by MIG welding technique

“…Being now in a meta-stable condition, solid solubility of the alloy is further reduced with decreasing the cryogenic temperature [36]. Thus, for the present material, it is possible to speculate under what condition partial super saturation of the solute elements occurs, where ultra-ne nodules of precipitate of phase (Mg 2 Al 3 ) emerge, particularly along the sub-grain boundary lines.…”

“…It has been recently noticed that during cryogenic cooling, alloying elements, such as Mg and Cu, become increasingly dense and ne throughout the matrix [36]. Particularly, ageing process right after cryogenic treatment yields Mg and Cu agglomeration at several zones, initially indicating coarse Mg-and Cu-rich zones that are getting ner and so homogenously distributed within the matrix.…”

“…When the material is kept at extremely low temperatures for elongated durations, the material tends to reach equilibrium conditions [32][33][34][35]. It is mostly claimed that microstructure gets ner during the process [36]. Thus, structure at about the welded joint after deep cryogenic treatment can be re ned, because there is a great temperature di erence during the cryogenic treatment.…”

The Influence of Deep Cryogenic Treatment (DCT) on the Mechanical Behaviour of Aluminium Metal Matrix Composites

“…Results showed that cryogenic treatment could improve the mechanical properties of aluminum alloy. Taskesenet al [10] analyzed the effect of CTT on the ageing behaviour of Al 7075-B4C composites. The hardness of the cryogenically-treated specimens increases considerably.Kumar et al [11] analyzed the impact of DCT on the wear rate of AISI D3 Die Steel using statistical tools.…”

Grain Size and Grain Boundary Analysis of Aluminum Compacts with/without 10 wt.% of Nickel Powder Processed by Equal Channel Angular Pressing

“…Low cost, lightness, resistance against corrosion, good ductility and aesthetic appearance are the most crucial properties of the Al alloys. Due to these properties, research of these alloys has been undergoing in the academic field and the potential for commercialization of these alloys has increased [1].…”