Coarsening of precipitates and dispersoids in aluminium alloy matrices: a consolidation of the available experimental data

Abstract

Experimental data on the coarsening of precipitates and dispersoids in aluminium-based matrices are reviewed. Available data are tabulated as K=(r ³−r ³₀ )/t where r ₀ is the initial particle radius and r is its value after time t at temperature T, and then plotted as log (KT) against 1/T for consolidation and assessment. The considerable body of data for δ′-A₃Li in Li-containing alloys is well represented by K=(K ₀/T) exp (−Q/RT) with K ₀=(1.3 ^+3.0_−0.5 ) × 10⁻¹³m³Ks⁻¹ and Q=115±4kJ mol⁻¹. The relatively limited data for θ′ and θ″ in Cucontaining alloys are representable by the same relationship with K ₀∼4 × 10⁻⁸ and — 4 × 10⁻¹⁰ m³ Ks⁻¹, respectively, and Q — 140 kJ mol⁻¹. Available data for coarsening of L1₂ ⁻ Al₃(Zr, V) and related phases in Zr-containing alloys and of Al₁₂Fe₃Si and related phases in Al-Fe based alloys indicate (i) rates of coarsening at 375 to 475 °C (0.7 to 0.8T_m) five to eight orders of magnitude less than would be expected for δ′, θ′ and θ″ in this temperature range, and (ii) high activation energies of ∼300 and 180 kJ mol⁻¹, respectively.