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Premartensitic Elasticity Of Fe-Ni Invars, Bryce Linn Shriver
Premartensitic Elasticity Of Fe-Ni Invars, Bryce Linn Shriver
Doctoral Dissertations
"The premartensitic temperature dependence of ultrasonic wave propagation in Fe-30 pct Ni polycrystals and Fe-32 pct Ni single crystals was measured by using a continuous wave technique. As the temperature was lowered to within 10°C of the Ms, a nonlinear decrease of the relative shear velocity was observed. This effect is related to dislocation stacking fault instabilities which may trigger the martensitic phase transformation. In addition, the single crystals show a frequency dependence of the shear elastic constant C' well above the Ms. The dispersion is believed to be caused by fluctuations in the anisotropic molecular …