Ad. Sequeira et al., BIMODAL SIZE DISTRIBUTIONS OF GAMMA' PRECIPITATES IN NI-AL-MO .2. TRANSMISSION ELECTRON-MICROSCOPY, Acta metallurgica et materialia, 43(9), 1995, pp. 3441-3451
Citations number
17
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
A double step aging procedure was used to produce bimodal size distrib
utions of precipitates in two Ni-Al-Mo alloys. The evolution of the mi
crostructure during the decomposition was studied using transmission e
lectron microscopy. Shape and changes in the spatial correlations of t
he precipitate ensemble as well as precipitate size distributions were
determined for a very wide time scale. Particle shape transitions dur
ing aging were monitored by the determination of aspect-ratio distribu
tions. The results are compared with small-angle neutron scattering an
alysis in the preceding paper and good agreement is found between the
size distributions determined by the two techniques. In the alloy with
high coherency strains peculiar phenomena were observed during aging,
e.g. coalescence among the small precipitates, preferential growth of
small precipitates in the presence of larger ones, and a dramatic nar
rowing of the size distribution of large precipitates indicating a uni
formization in size towards late stages of aging.