# Influence of Heat Treatment Parameters on Microhardness of Aluminium Alloy EN AW 7075 Foams and Bulk Material

## TL;DR

This study explores how heat treatment affects the hardness of aluminum alloy foams and bulk material, finding optimal conditions for maximum microhardness.

## Contribution

The study identifies optimal heat treatment parameters for maximizing microhardness in EN AW 7075 aluminum alloy foams and bulk material.

## Key findings

- Bulk material reached maximum microhardness of 158 ± 2 HV1 at 175 ± 1 °C for 2 ± 0.02 h.
- Foams achieved highest microhardness of 150 ± 2 HV1 at 150 ± 1 °C for 9 ± 0.02 h.
- Optimal artificial ageing condition was determined as 150 ± 1 °C for 2 ± 0.02 h.

## Abstract

Aluminium alloy foams have been widely used due to their excellent strength-to-weight ratio, low density, and outstanding properties such as high energy absorption and effective noise and heat insulation. In this study, aluminium machining chips have been used for foam production as a potential recycling method. The process has involved solution heat treatment followed by artificial ageing. Researchers have been analysing the microhardness of both the foam and the bulk material, as well as examining their microstructures. The maximum microhardness value of the bulk material has been found to be 158 ± 2 HV1 at an ageing temperature of 175 ± 1 °C for 2 ± 0.02 h. For the foams, the highest microhardness of 150 ± 2 HV1 has been achieved after ageing at 150 ± 1 °C for 9 ± 0.02 h. Experimental planning has been carried out using Design Expert software. The optimisation process has identified 150 ± 1 °C for 2 ± 0.02 h as the optimum condition for artificial ageing.