Evaluation of the Mechanical Properties of Metals by means of an Instrumented Ultramicrotome

Recently, the instrumented ultramicrotome, which can measure the cutting force required to shave off a thin film for TEM observation with ultramicrotomy, has been developed. In this study, the cutting force of various metals was measured with the instrumented ultramicrotome to reveal their mechanical properties which the measured cutting force reflects. A pure Pb, Al, Zn and Cu were used as specimens. The measured cutting force tended to have a little relationship with Vickers hardness of the specimens. Especially, the cutting force showed almost constant value without depending on the Vickers hardness in the pure Cu specimens whose hardness was varied with a cold rolling and an annealing. Therefore, the shear stress of the specimens, which is needed to deform the thin film, was estimated with assuming that the measured cutting force consists of two elements, the shear stress and the tear force which is needed to remove a thin film from a specimen block. The shear stress was unique to each specimen, and it had a good relationship with the shear modulus of specimen. The value of the shear stress was about 1/60 of the modulus in each specimen. This indicates that dislocations are not concerned with the shear deformation in the thin films of 100∼300 nm in thickness obtained with ultramicrotomy.