Wear-Resistant Al—Steel Mixtures Produced by PM Technique Which Avoids Sintering

Abstract

Alloys having particularly advantageous properties can be produced by PM techniques in which the sintering operation is avoided. This is made possible by compaction by discrete shock waves where the work of compaction is used to heat the interparticle boundaries preferentially. Thus non-equilibrium powders may be consolidated without the chemical reactions, or degeneration of metastable microstructures, which would occur during sintering. One such alloy is the Al-steel mixture which, if sintered, would undergo a thermite-type reaction. The compaction technique allows a wide freedom of alloying parameters; it has thus been possible to determine some of the effects on wear resistance of the type, shape, size, hardness, and percentage addition of the hard phase. It has been found that the properties required of the hard phase change with the wear situation. As a general rule, the wear decreases as the percentage of hard phase increases and the hard phase should at least be harder than the material it is rubbing against. The adhesive and abrasive wear of the Al-steel PM alloys are comparable to those of a medium-alloy steel, while the seizure resistance can approach that of cast iron. The mechanical properties are similar to those of wrought aluminium alloys; the transverse rupture stress ranges from 150 to 400 MN m⁻² and the hardness from 70 to 180 HV.