Nanomechanical characterisation of solid surfaces and thin films

Depth-sensing nanoindentation measurement techniques are commonly used to measure nanomechanical properties of surface layers of bulk materials and of ultrathin coatings. The nanoindentation apparatus continuously monitors the load and the position of the indenter relative to the surface of the specimen (depth of an indent) during the indentation process. Mechanical property measurements can be made at a minimum penetration depth of about 20 nm (or a plastic depth of about 15 nm). In this paper, mechanical property measurements using nanoindentation techniques are reviewed and discussed. Emphasis is given to the use of sharp indenters and how they can be used to measure hardness, elastic modulus, continuous stiffness, scratch resistance, film-substrate adhesion, residual stresses, time dependent creep and relaxation properties, fracture toughness, and fatigue. Applications of the continuous stiffness measurement technique to the characterisation of multilayered structures and graded materials are presented. Recent progress in the development of the nanofatigue measurement technique is briefly reviewed. Directions for future research in nanoindentation are discussed.