Effect of mechanical activation time on structure and mechanical properties of W-Cu powder composite

Mixtures of tungsten-copper powders (88.2 wt. % W + 11.8 wt. % Cu) with different granulometric composition after mechanical activation at different process times were studied. Before mechanical activation, W particles have a size of about 4 μm, and large agglomerates of tungsten particles are ~20 μm. The structures and elemental composition of W-Cu powder samples before and after mechanical activation (1, 3, 5, and 10 min) were studied by scanning electron microscopy and X-ray microanalysis. The strength (compression) tests of pressed samples in a cylindrical matrix 12 mm in diameter were carried out on an Instron 3382 testing machine. Powder compaction curves were obtained, the dependences of the pressing stress on density were plotted, and the dependence of the sample density on the mechanical activation time was determined. As a result of strength tests, the dependences of stress on strain were obtained. The highest density of the mixture is achieved when the duration of treatment in the mechanical activator is 5 min. A further increase in the processing time of the mixture leads to the grinding of the powder and the destruction of the agglomerates. The average particle size of the powder decreases, which leads to a deterioration in the compaction of the samples. At the same time, with an increase in the treatment time to 10 min, the distribution of copper particles over the sample improves simultaneously with a decrease in the size of its particles to 100 – 400 nm, which, apparently, affects the increase in strength.