Combustion Synthesis and Structure of Porous Ti-Si Intermetalics Material

Porous Ti-Si materials were prepared by a combustion synthesis method. The atomic ratios of Ti:Si were 1:1, 5:4, 5:3 and 3:1. The combustion characteristics, phase composition, pore structure and microstructure of the products were investigated. It is found that, with the increase of Ti content, the rate of the combustion wave and the combustion temperature first increase and then decrease, and-the highest combustion temperature is 2075 K. The main products are TiSi, Ti5Si4, Ti5Si3 and Ti5Si3 at the Ti:Si atomic ratios of 1:1, 5:4, 5:3 and 3:1, respectively. The open porosities of the products are within the range of 42.43%similar to 49.42%. The median pore diameters are within the range of 64.10 similar to 18.11 mu m and decrease with the increase of Ti content. The highest compressive strength is 23.15 MPa. The main pore formation mechanism includes the residual pores among the particles of the powder compacts, and the in situ pores owing to the molten silicon particles flowing during the combustion synthesis reaction. The large pores are formed by the interstitial hole combining with the in situ pores, and the small pores are formed by the decrease of the molar volume during the solution-precipitation process.