Mechanical Properties of Nanostructured Niobium on a Microscopic Scale

Abstract

The nanoindentation technique is a well established method to determine the mechanical properties (hardness, Young’s modulus) of small volumes of materials or thin films. Results obtained by this technique are usually interpreted and discussed with respect to the classical continuum approach. For example, for an ideal elastic-plastic material hardness and Young’s modulus have to be independent of the indentation depth. This behavior has also been observed for nanostructured niobium. The specimens were produced via mechanical attrition resulting in an average grain size of approximately 10 nm. On the microscopic scale the hardness varies between 4 and 7 GPa. This value is 3–6 times higher than that of polycrystalline niobium. Young’s modulus was determined to be 80±30 GPa which despite the large scatter is smaller than values for polycrystalline Nb (95±15 GPa).