Some observations on hardness measurements of particulate-reinforced 6061 aluminum metal matrix composites

Hardness measurements on a series of particulate- reinforced metal matrix composites in a solution treated and T- 6 condition were carried out using a Vickers microhardness tester at 25-, 50-, 100-, 200-, 300-, and 500-g indenter loads and a Vickers macrohardness tester at an indenter load of 5 kg. It appears that the presence of the particles makes a contribution to the hardness measurement, the degree of which depends on the size and distribution of the particles, and also the indentation load. Although some trends are observed, there is no predictable effect of the material and test parameter on the hardness values.