THERMOMECHANICAL EFFECTS IN THERMAL-EXPANSION OF AR-N-2-TYPE SOLID-SOLUTIONS

The results of analysis of hysteresis in the thermal expansion of soli d solutions Ar-4.89 mol. %N-2 are considered in the temperature range 1-16 K. A physical model is proposed in order to explain the observed phenomenon. This model is based on the assumption that transformed reg ions in the form of piles of random stacking faults in the initial fee lattice are formed in the vicinity of nitrogen impurity. The hysteres is of the thermal expansion coefficient is due to relaxation mechanism s for thermal stresses appearing in the transformed region during ther mocycling of the sample. The theoretical estimates of the upper and lo wer temperature boundaries of hysteresis phenomenon obtained in this m odel are in good agreement with the experimentally observed values. (C ) 1997 American Institute of Physics.