Proposal for a hardness measurement technique without indentor by gas-cluster-beam bombardment

Large gas-cluster-ion bombardment has been shown to be a unique tool for generating a variety of bombarding effects over a broad range of acceleration energies. A hardness measurement technique is proposed in this paper based on the use of the effect of crater formation by large gas-cluster beams. The cluster impact leaves a hemispherical crater on a surface, the size of which varies with surface hardness and cluster parameters (which can be predetermined). As shown in this paper, the crater depth h (or diameter d) and Brinell hardness B are correlated through the formula $h\sim {\mathrm{}(E/B)\mathrm{}}^{1/3},$ where E is the cluster acceleration energy. The material hardness, binding energy, and the crater size have also been correlated with the sputtering yield Y, and hence this correlation can also be experimentally applied for measuring hardness. The proposed method is based entirely on surface effects which depend only on the surface material and not on the substrate and therefore should be particularly suitable for measuring hardness of thin deposited films. This technique also eliminates the need for indentors that are harder than the material measured.