DEVELOPMENT OF HIGH TEMPERATURE ULTRA-MICROINDENTOR USING LASER-PHASE-MODULATION-INTERFEROMETER

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Ultra-micro-indentor is the only one method for the direct-measurement of hardnesses and mechanical properties in micro area, and is expected to be applied to material-development and products-management. It is, however, the present situation that the generalization of this measurement-technique is behind because of the technical difficulties at relatively high temperature. In the existing technique, the micro displacement of indentor is indirectly measured by a electric capacitance, therefore the influence of thermal expansion causes errors. The purpose of the present study is the establishment of the fine measurement technique at high temperature, solving the problem of thermal expansion with the direct measurement of the relative displacement between the indentor and sample surface, using a up-to-date laser measurement technique. In the first fiscal year (1995), we developed a laser-phase-modulation-interferometer for the measurement of vertical displacement, and made a design and a trial manufacture of an indentor which introduce the laser beam to the sample surface. The indentor have a hole with 1mm diameter at 1mm distance from the central axis, and have a half-mirror within the hole. The relative displacemet between the indentor and the sample surface is directly measured by interfering the two beams reflected by the mirror and the sample surface. In the fiscal year of 1996, we installed the indentor to an existing micro indentation testing machine and estimated the efficiency from various points of view. The maximum resolution is 1nm. We also found the necessity of fine adjustment of the slope of the sample stage, because the incident angle of the reflected beam to the optical fiber strongly influence the resolution. It is pointed that, if such conditions are satisfied, the ultra micro indentation test at high temperature is available with the same procedure and accuracy as at room temperature avoiding the temperature influence.