Development of an Atomic Force Microscope Ultra-Microhardness Tester with a Silicon Tip for High-Resolution AFM Imaging

Abstract

A combined instrument for ultra-microhardness testing and atomic force microscopy (AFM) has been developed. The instrument could be employed to conduct hardness tests with a diamond indenter and its Si tip allowed high-resolution AFM images to be obtained at the same position on the specimen. Ultra-microhardness tests and AFM observations were carried out on electrolytically polished specimens of a tungsten single crystal and JIS-SCM415 and JIS-SCM440 low-alloy steels. The SCM415 and 440 steels were tempered at 873K and 723K, respectively. The benefits of using a Si tip instead of a diamond indenter for AFM observation are clearly shown by the better profile of the indent mark on the tungsten single crystal and the clearly distinguishable images of the fine carbides of the steels. The ultra-microhardness of the steels was influenced by the local microstructures such as the carbide density and the presence of a ferritic phase.