Synthesis, microstructure and properties of Ti–Al porous intermetallic compounds prepared by a thermal explosion reaction

Abstract

Ti-Al porous intermetallic compounds were prepared by a simple and energy-saving process of thermal explosion (TE) reactions. The effects of the Ti/Al molar ratios (including Ti : Al ¼ 3 : 1, 2 : 1, 1 : 1, 1 : 2 and 1 : 3) on the temperature profiles, phase compositions, pore characteristics, density, expansion behaviors and oxidation resistance were investigated. The ignition temperatures were between 630-653 C and the combustion temperatures were between 737-1161 C, both of which are higher than the target furnace temperature. Porous Ti-Al alloys displayed a high open porosity of 35-56%. The pores were from non-fully dense green compacts and expansion behaviors of TE. When the target furnace temperature was set at 650 C, the specimen with Ti and Al in a 1 : 2 ratio possessed the highest open porosity of 53.89% and the lowest density of 1.58 g cm À3 . When the target furnace temperature was set at 700 C, the specimen with Ti and Al in a 1 : 3 ratio possessed the highest open porosity of 56.27% and the lowest density of 1.44 g cm À3 . The porous specimens with Ti and Al in a 1 : 3 ratio exhibited the best resistance to oxidation at 650 C in air.

Aluminium matrix tungsten aluminide and tungsten reinforced composites by solid-state diffusion mechanism

“…The formation mechanism of intermetallic compound during in-situ processing can be explained by diffusion process 19 or thermal explosion (TE) 20 . Sun et al .…”

Microstructure Evolution and Pore Formation Mechanism of Porous TiAl3 Intermetallics via Reactive Sintering

“…It is necessary to mention that the major limitation of these researches is long sintering time and thus present a high energy consumption route. Yet there are researches which reported that the pore formation mechanism of porous Ti-Al materials depends on the thermal explosion (TE) reaction, accompanied by a large amount of heat release [17][18][19]. Contrary to Kirkendall effect, the bulk specimen was ignited by a constant heating rate and the reaction occurred over the whole specimen to the ignition temperature during TE [20].…”

“…In addition, TE is a highly exothermic reaction, and hence has the advantage of low energy consumption, simplicity of equipment and short sintering time [3]. Wang et al [19] prepared porous TiAlbased intermetallics via TE with high open porosity of 84%, and the total sintering time only took about 6 h. Porous TiAl 3 intermetallics have the higher oxidation resistance in Ti-Al system, compared to Ti 3 Al and TiAl phases and relative low density [3,18,21]. Shi et al [18] studied the effect of Ti/Al molar ratios on pore structures of porous Ti-Al intermetallics, and the specimen with Ti/Al molar ratio of 1:3 showed excellent high-temperature oxidation resistance at 650°C.…”

“…Wang et al [19] prepared porous TiAlbased intermetallics via TE with high open porosity of 84%, and the total sintering time only took about 6 h. Porous TiAl 3 intermetallics have the higher oxidation resistance in Ti-Al system, compared to Ti 3 Al and TiAl phases and relative low density [3,18,21]. Shi et al [18] studied the effect of Ti/Al molar ratios on pore structures of porous Ti-Al intermetallics, and the specimen with Ti/Al molar ratio of 1:3 showed excellent high-temperature oxidation resistance at 650°C. Those studies focused more attention about the influence of sintering factors on the pore structures and combining with pore-forming agent to prepare the high porosity of porous Ti-Al materials.…”

Amino Acids Aided Sintering for the Formation of Highly Porous FeAl Intermetallic Alloys

“…However, other approaches have also been developed in order to obtain metallic foams. For example, Shi et al reported the fabrication of porous Ti-Al alloy with thermal explosion (TE) reaction during the sintering [ 27 ]. Another approach that is easy to apply during sintering is in-situ gas release.…”