Emerging technologies for the in-situ production of MMCs

Abstract

Among the numerous methods of producing discontinuously reinforced metal-matrix composites, technologies allowing insitu production of the reinforcing phase offer significant advantages from a technical and economic standpoint. The in-situ formation of a ceramic second phase provides greater control of the size and level of reinforcement, yielding better tailorability of the composite properties. As an example, significantly finer ceramic particulates are possible, which minimizes toughness degradation that is traditionally associated with composites containing relatively large particles. Several emerging, innovative technologies in this area are under development. As with any new technology there are technical challenges, but it is believed that these processes have unique capabilities and, thus, they present cost-effective production processes for metalmatrix composites.

On the Formation and Distribution of In Situ Synthesized TiB2 Reinforcements in Cast Aluminium Matrix Composites

“…The formation of the TiB 2 reinforcement in composite depends on the thermodynamics and kinetics of the reaction between the halide fluxes and molten aluminium. Many combinations of fluxes are available [7]. In the present work, K 2 TiF 6 and KBF 4 were used for the synthesis of Al-TiB 2 composites.…”

“…Some of the synthesis systems for Al-TiB 2 composites are TiO 2 -Al-B, TiO 2 -Al-B-CuO, TiO 2 -Al-B 2 O 3 , NaBH 4 and TiCl 4 and Ti-containing and B-containing salts. The synthesis occurs via a series of chemical reactions which produce sub-micron TiB 2 particles in the aluminium melt [6][7][8]. Different techniques/methods such as powder metallurgy, spray deposition and several casting methods (rheo-casting, squeeze-casting, stir-casting and compo-casting) are used to obtain TiB 2 reinforcement in aluminium matrices.…”

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

“…Thermal plasma evaporation process utilized high energy of plasma to synthesize AlN and Al-AlN particles within several minutes. 16 In the process, however, in situ formed particles were very small in size (50 nm in diameter) and the particles should be sintered with Al powders to produce bulky Al-AlN composites. 11 In sum, although various approaches for fabricating in situ AMCs with AlN by nitridation of Al melt have been proposed, we are still far away from continuous production of in situ AlAlN composites with attractive thermal properties through cost-effective processing.…”

The Effect of Reinforcement Ratio on the Wear Behaviour of AlB2Flake Reinforced Metal Matrix Composites

“…This method provides a potential to fabricate composites with the required thermodynamic stability while minimizing damage to the strengthening phase. Moreover, in situ formation of a second phase provides greater control of the size and level of reinforcement while maintaining excellent reinforcement-matrix compatibility [7].…”