The grain structure and texture evolution during annealing a Al-0.13% Mg submicron-grained alloy, deformed by plane-strain compression (PSC) at cryogenic temperatures, has been investigated by transmission electron microscopy and electron backscatter diffraction. After deformation the alloy contained a lamellar grain structure with a high-angle grain boundary (HAGB) spacing of 190 nm and an area fraction of $80%. On annealing the grain structure coarsened and transformed from lamellar to equiaxed. Remarkably, the fraction of low-angle grain boundaries (LAGBs) progressively increased during annealing, to $50% above 300°C, leading to instability and discontinuous recrystallization at higher temperatures. This resulted in a ''bimodal grain structure" comprised of bands of coarser grains and fine subgrains, arising as a result of the increase in proportion of lower-mobility LAGBs. The surprisingly large increase in LAGB fraction on annealing is shown to be related to orientation impingement, originating from the strong texture present after PSC in liquid nitrogen.
a b s t r a c t B 4 C powders were synthesized by carbothermal reduction of ethylene glycol (EG) added borate citrate precursors, and effects of EG additions (0-50 mol% based on citric acid) on the morphologies and yields of synthesized B 4 C powders were investigated. The conditions most suitable for the preparation of precursor were optimized and optimum temperature for precursor formation was 650 • C. EG additions facilitated low-temperature synthesis of B 4 C at 1350 • C, which was around 100-300 • C lower temperature compared to that without EG additions. The lowering of synthesis temperature was ascribed to the enlargement of interfacial area caused by superior homogeneity and dispersibility of precursors enabling the diffusion of reacting species facile. The 20% EG addition was optimal with free residual carbon lowered to 4%. For smaller EG additions, the polyhedral and rod-like particles of synthesized product co-existed. With higher EG additions, the morphology of synthesized product was transformed into needle and blade-like structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.