微小セメンタイト粒子のAFM超微小硬さ試験

概要

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The hardness of cementite spheroidized S 25 C steel was measured, using an AFM ultramicro hardness tester and a special lever that has a three-sided pyramidal diamond indenter with an apical angle of 60°. A clear AFM image of the specimen surface etched in a solution of 3% nitric acid and 97% alcohol enabled us to distinguish small cementite particles with a diameter of less than 1μm. Using AFM imaging, we obtained force-penetration curves for small cementite particles as well as the ferrite portion of S 25 C steel. The curves show yield behavior. Below the yield force where the penetration depth was less than 30 nm, the experimental curve agrees well with the theoretical one. The normalized yield stress, τ_y/G, is 0.46 for cementite particles and 0.24 for the ferrite portion. These values are nearly equal to those for glass and silicon, and for SNCM 439 steel, respectively. It is concluded that the hardness measurement of the materials containing small particles was realized in the nanoscopic region, using the AFM ultramicro hardness tester with a special lever having a three sided pyramidal diamond indenter with an apical angle of 60°.
一般社団法人日本機械学会の論文
1998-02-25