Mechanical Properties of Al-Al₄C₃ Composite Produced by Mechanical Alloying

Abstract

The aim of this paper was to study the influence of different input materials and methods of treatment on the microstructure, mechanical properties and fracture of dispersion strengthened aluminium alloys in the Al-Al 4 C 3 system. It was proved that the transformation efficiency of carbon to Al 4 C 3 by heat treatment of aluminium with the porous furnace black and electrographite is higher than that of the hard cracked graphite. The size of Al 4 C 3 dispersed phase was measured by TEM on thin foil and it was constant and as small as 30 nm. Subgrain size measured in the range of 100 grains in thin foils depended on the carbon type, as well. It ranged from 0.3 to 0.7 µm. The temperature dependence of ductility, and reduction of area in the temperature range of 623 -723 K and strain rate of 10 -1 s -1 , indicated a considerable increase of properties. In a case when the volume fraction of Al 4 C 3 changes from lower to higher, the grain rotation mechanism dominates instead of the grain boundary sliding. The dependence of the minimum deflection rate on the applied force as well as the dependence of the time to fracture on the applied force for two temperature levels (623 and 723 K) by small punch testing is depicted. The anisotropy of the creep properties and fracture using small punch tests for the Al-Al 4 C 3 system produced by ECAP were analysed.

Contamination in wet-ball milling

“…Dispersoids of refractory compounds could be beneficial; they can be exploited in increasing the hardness and creep resistance of alloys [35]. For example, in Al alloys, it is shown how added carbon, besides serving as a PCA acts as dispersoid precursor for carbides, which results in a strengthening effect [38]. Further, precipitation of such compounds can also increase the material's toughness in brittle materials.…”