V. Seetharaman et Sl. Semiatin, ANALYSIS OF GRAIN-GROWTH IN A 2-PHASE GAMMA-TITANIUM ALUMINIDE ALLOY, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 28(4), 1997, pp. 947-954
Microstructure evolution during annealing of a wrought near-gamma tita
nium aluminide alloy, Ti-45.5Al-2Nb-2Cr (at. pct), in the temperature
range 1200 degrees C to 1320 degrees C was investigated. The mean grai
n size of the alpha phase as well as the volume fraction and size of t
he gamma particles were evaluated as a function of annealing temperatu
re and time. Isothermal annealing at temperatures above the alpha tran
sus, T alpha = 1300 degrees C, led to rapid grain growth of the alpha
phase, the kinetics of which could be described by a simple power-law
type expression with a grain growth exponent p = 2.3. Alpha grain grow
th was significantly retarded during annealing at subtransus temperatu
res (1200 degrees C < T less than or equal to 1300 degrees C) by the p
inning influence of gamma-phase particles. Limiting grain size values
predicted by computer simulation models applicable for high-volume fra
ctions of precipitates/particles were in good agreement with experimen
tal findings. The kinetics of alpha grain growth in the presence of ga
mma particles were analyzed, and the results showed that a grain growt
h exponent of p approximate to 2.6 could satisfactorily account for th
e experimental results.