Dynamic heat flux experiments in Cu67.64Zn16.71Al15.65: Separating the time scales of fast and ultra-slow kinetic processes in martensitic transformations

Abstract

Crackling noise and avalanches during the martensite phase transformation of Cu67.64Zn16.71Al15.65 were investigated. Heat flux measurements with extremely slow heating rates of 0.005 Kh−1 allowed sufficient separation between the continuous background and the avalanche jerks. The jerk enthalpy is below 3% of the total transformation enthalpy. The crackling noise follows power law behavior with an energy exponent near ɛ = 1.8. The jerks are almost uncorrelated with approximately a Poisson distribution of the waiting times between jerks. Quantitative analysis showed a scaling behavior with p(wt) ∼ wt(γ−1)exp(−wt/τ)n with γ = 0.7 and n ≈ 1.