ANALYSIS OF THE FORMATION MECHANISM OF TiB_2 PARTICULATE FABRICATED BY IN SITU REACTION IN MOLTEN ALUMINIUM
YANG Bin; WANG Yuqing;ZHOU Benlian (Institute of Metal Research; The Chinese Academy of Sciences;Shenyang 110015)(Department of Mechanical and Electronic Engineering; Nanchang University; Nanchang 33002)(International Center for Materials Physics; The Chinese Academy of Sciences; Shenyang 110015)
Cite this article:
YANG Bin; WANG Yuqing;ZHOU Benlian (Institute of Metal Research; The Chinese Academy of Sciences;Shenyang 110015)(Department of Mechanical and Electronic Engineering; Nanchang University; Nanchang 33002)(International Center for Materials Physics; The Chinese Academy of Sciences; Shenyang 110015). ANALYSIS OF THE FORMATION MECHANISM OF TiB_2 PARTICULATE FABRICATED BY IN SITU REACTION IN MOLTEN ALUMINIUM. Acta Metall Sin, 1998, 34(1): 100-106.
Abstract By making use of a technique in which TiB2 particulates are formed by an in situ reaction in molten aluminium, TiB2/Al composites have been fabricated. The formation mechanism of TiB2 particulate was studied with XRD and SEM. The results show that (1) the heat generated by the reaction 3Al1+Tis→Al3Ti is one of reasons for igniting the reactions Al3Ti+2B→ 3Al+TiB2 and Ti+2B →TiB2, (2) diffusion, solution-precipitation mechanisms occur during this process and (3) both theoretical and experimental results have shown that the effect of aluminium content in the preform on the formation mechanism of TiB2 particulate is much obvious. When the mole fraction of aluminium in the preform exceeds 43.5%, TiB2 particulates are formed by a diffusion mechanism, and the morphology of the particulates is approximately spherical. A part of TiB2 particulates is formed by a solution-precipitation mechanism when the mole fraction of aluminium is lower than 43.5%, and the TiB2 particulates have grown up to square and multilateral shape. A number of square and multilateral TiB2 particulates with growing steps have been clearly observed with SEM.
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