A Study of Nanostructured 7034 Aluminium Alloy: Relationship Between Microstructure and Mechanical Properties

The study focuses on a 7000 series aluminium alloy (grade 7034), produced by melt spinning, a process based on the rapid solidification process (RSP).The aim of this process is to obtain a "nanostructured" material whose mechanical properties are improved through grain size refinement.This article addresses the influence of different heat treatments, in addition to the process itself, on the alloy's microstructure and mechanical properties.The aim of the study is therefore to provide a comparative metallurgical analysis of the alloy in different tempers (as extruded, T6 heat treated and annealed) using advanced observation methods (FEG-SEM, EDS, EBSD), physical tests (DSC, electrical conductivity) and mechanical tests (tensile and hardness tests).To establish the influence of heat treatment steps, this paper identifies the nature, size and distribution of the various alloy phases and determines the dislocation density and the grain size.It correlates the macroscopic mechanical behaviour with the microstructure, notably by establishing a direct relationship between the microstructure and the mechanical properties, thereby enabling the yield strength value to be predicted by determining the individual contribution of each alloy hardening mode: grain refinement (Hall-Petch equation), solid solution, density of geometrically necessary dislocations, and precipitation (JMAK model).Finally, it appears that the nanostructure contributes significantly to the overall hardening of the alloy and that it is greater than observed on 7000 series alloys produced by conventional processes.