Crystallization mechanism and microstructure evolution of Li2O–Al2O3–SiO2 glass-ceramics with Ta2O5 as nucleating agent
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Li2O–Al2O3–SiO2 glass-ceramics were prepared with Ta2O5 as nucleating agent, the crystallization mechanism and microstructure evolution were investigated by DTA, XRD, and SEM technologies. With increasing amount of Ta2O5 from 2 to 6 mol%, the crystallization activation energy decreased from 297.73 to 218.66 kJ mol−1, while the crystallization index increased from 1.76 to 3.39. In addition, the cluster of dendritic crystals and lamellar structure obtained in T-2 glass-ceramics indicated a typical two-dimensional crystallization mechanism, and the formation of spherical β-quartz solid solution in T-4 specimens, with average size of 50–70 nm, was mainly due to bulk crystallization mechanism. It was considered that Ta2O5 promoted the nucleation and crystallization of LAS glass by precipitating the crystalline precursor phase of Ta2O5, which acted as nuclei for the subsequent crystal growth. Eventually, the diffusion and crystallization process, microstructure morphology, as well as the secondary grain growth were also investigated.
KeywordsGlass ceramics Crystallization Microstructure-final Grain growth Ta2O5
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