Influence of Supercooling Level on Kinetics of Phase Separation in Solid Mixtures of 4He in 3He

We studied the kinetics of phase separation in the solid mixture of 4 He in 3 He at various supercooling in the temperature range of 100-200 mK through precise pressure measurements. The time dependences of the pressure change during phase separation were exponential. At small supercooling the characteristic time constant (tau) is almost independent of the final temperature Tf and is about 10 hours, which is considered to result from heterogeneous nucleation. In a narrow range of Tf (tau)decreases more than an order of magnitude. At larger supercooling (tau)is independent of Tf again. This behaviour agrees qualitatively with the theoretical consideration of the phase separation kinetics at homogeneous nucleation taking into account the finiteness of a cooling rate. The value of interphase surface tension has been obtained from comparison of the theory with the experimental results.