The mechanism of formation of TiB2 particulates prepared by In Situ reaction in molten aluminum

Abstract

By making use of a novel technique in which TiB 2 particulates are fabricated by an in situ reaction in molten aluminum, we have successfully produced TiB 2 /Al composites. In order to reveal the characteristic of the technique, the mechanism of formation of TiB 2 particulates obtained by this method is studied in this article. Both theoretical and experimental results have shown that the TiB 2 particulates are formed by a diffusion mechanism when the molar fraction of aluminum in the preform is higher than 43.5 pct. In this case, the TiB 2 particulates are generally spherical, and their mean size is less than 2.0 m. On the contrary, the TiB 2 particulates are formed by a solutionprecipitation mechanism when the fraction is lower than 43.5 pct. In this case, the TiB 2 particulates are multifaceted, and the size of most particulates lies between 3.0 and 6.0 m.

EFEITOS DA ADIÇÃO DO INOCULANTE Al-3%Ti-1%B ÀS LIGAS DO SISTEMA Al-Si

“…(1) As ligas-mãe do sistema Al-Ti-B contêm dois tipos diferentes de partículas. Um primeiro tipo é o diboreto de titânio (TiB 2 ), que é um material cerâmico muito estável e inerte, (2) presente na forma de partículas com tamanhos na faixa de 1 a 2 µm e uma estrutura cristalina hexagonal que não se dissolve no alumínio líquido. (3) O segundo tipo de partícula é o alumineto de titânio (TiAl 3 ), com tamanhos na faixa de 30 µm a 50 µm, que se dissolve significativamente em poucos segundos no alumínio fundido.…”

The effect of multiple laser alloyed tracklines on the corrosion properties of Al-MMC

“…1 Surface treatment is a promising way to increase the surface/cross section hardness, wear, and corrosion resistances of metals in order to develop new industrial applications. [1][2][3][4][5][6][7] LSA can be utilized to tailor the surface properties of metals as desired for specific applications without alteration of the core microstructure or the bulk properties. One of the most efficient surface modification methods to improve the tribological and corrosion properties of metals/alloys is laser surface alloying ͑LSA͒.…”

“…With conventional surface treatment of metals, it is difficult to achieve significant improvement in surface dependent properties such as wear, erosion, and corrosion resistances. 1,2,[4][5][6][7][8] Production of multiple tracklines involves overlapping of single tracklines corresponding to the width of the laser beam, the overlap zone in between tracklines will be subjected to an additional heat treatment and a double powder deposition, which is not received by the other zones, and this means the heat received is not homogeneous across the surface of the material treated. Aluminum alloys reinforced with additions of fine ceramic particles can find use in many industries especially because of the weight savings associated with light metals.…”

In-Situ MMC Production through VXBY Intermetallics Formation in an Al Matrix

“…The latter, plays a critical role in the final MMC properties and has been the incentive for the development of in-situ MMCs. In such a MMC the reinforcing phase is formed in situ in the metallic matrix through chemical reactions among the elements and/or compounds during the fabrication process [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. This approach results in a MMC containing a finer dispersion of reinforcements, which are thermodynamically stable and with improved matrix-reinforcement interface properties.…”