Development of an AFM Ultra-Micro Hardness Tester with a Si tip for High-Resolution Imaging.

Abstract

A combined instrument of ultra-micro hardness testing and atomic force microscopy (AFM) was developed. The instrument was able to conduct hardness test by a diamond indenter and to obtain high-resolution AFM images by a Si tip, at the same position of a specimen. Ultra-micro hardness test and AFM observation were carried out for electrolytically polished specimens of tungsten single crystal and low-alloy steels SCM 415 and 440. The SCM 415 and 440 steels were tempered at 600 and 415°C, respectively. The benefit of using a Si tip instead of a diamond indenter for AFM observation is clearly shown by the better profile of the indent mark on the tungsten single crystal and the distinguished image of fine carbides of the steels. The ultra-micro hardness of the steels was influenced by the local microstructures such as the carbide density and the presence of ferritic phase.