COARSENING OF PRECIPITATES AND DISPERSOIDS IN ALUMINUM-ALLOY MATRICES - A CONSOLIDATION OF THE AVAILABLE EXPERIMENTAL-DATA

Experimental data on the coarsening of precipitates and dispersoids in aluminium-based matrices are reviewed. Available data are tabulated as K = (r(3)-r(0)(3))/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 delta'-Al3Li in Li-containing alloys is well represented by K=(K-0/T) exp (- Q/RT) with K-0= (1.3(-0.5)(+3.0)) -0.5 x 10(-13) m(3) Ks(-1) and 0 = 115 +/- 4 kJ mol(-1). The relatively limited data for theta' and theta'' in Cu-containing alloys are representable by the same relationship with K-0 similar or equal to 4 x 10(-8) and similar or equal to 4 x 10(-10) m(3) Ks(-1), respectively, and Q similar or equal to 140 kJ mol(-1). Available data for coarsening of L1(2)- Al-3 (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 degrees C (0.7 to 0.8T(m)) five to eight orders of magnitude less than would be expected for delta', theta' and theta'' in this temperature range, and (ii) high activation energies of similar to 300 and 180 kJ mol(-1), respectively,