Development of a mechanical spectroscopy measurement system for an extended temperature range and its applications.

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(1) Development of the systemA system for characterizing the elasticity and anelasticity of solids has been successfully developed, which works by the forced-vibration method in the frequency range between 10^<-5> Hz and 10 Hz from room temperature to 1,000℃. It measures the relation between the stress and strain (the real and imaginary parts of the complex elastic modulus) under forced torsional vibration of a rod or plate-shaped specimen, of 0.5-1 mm in thickness and 10-50 mm in length, with a strain amplitude between 10^<-5> to 10^<-4>. The measurement sequence is fully automated with a computer. With the temperature held constant, measurements are repeated with sweeping the frequency, thereby obtaining the elastic modulus and internal friction as functions of frequency. It is also capable of free-decay measurements in resonance vibration, at a constant temperature or under a steady temperature variation.(2) ApplicationsAnelastic relaxation due to jumps of antisite atoms in L1_2 ordered alloys has been measured, from which the jump rates of the atoms and the diffusion coefficients have been successfully evaluated. The relaxation effects due to stress-induced reorientation of interstitial solute atoms in bcc metals have been systematically measured, and it has been verified that the instrument can determine the relaxation strengths and relaxation rates at satisfactory accuracy.