Growth morphology and microstructural characterization of nonstoichiometric Ti2AlC bulk synthesized by self-propagating high temperature combustion synthesis with pseudo hot isostatic pressing

Thermal shock behavior of Ti2AlC from 200°C to 1400°C

“…From the figure it can be seen that the thermal shock behavior of the MAX phases is strongly affected by the grain size: the flexural strength for Ti 3 SiC 2 for example has no significant degeneration in the coarse‐grained (100‐200 μm) sample even with a quenching temperature above 1200°C, while for the fine‐grained sample (3‐5 μm) it deceases sharply for quenching temperatures around 500°C‐700°C. It follows that in the present work the fine‐grained (3.05 μm) microstructures of Ti 2 AlC fabricated by the SHS/PHIP process are the reason for the lower thermal shock resistance in the present work.…”

“…The procedure for fabricating large‐scale Ti 2 AlC bulk samples used in the present work is described elsewhere, and is very similar to that employed in our previous work . In short, disk‐shaped pellets of bulk Ti 2 AlC, 150 mm in diameter and 20‐30 mm in height, were fabricated by use of the SHS/PHIP process under a pressure of ~250 kN for ~25 s in a steel mold, with a starting powder mixture of Ti (99.2%, 36 μm), Al (99.5%, 12 μm), and carbon black (99.0%, 1 μm) with Ti:Al:C molar ratios of ~2.9:2:1, which corresponds to the derived nonstoichiometric Ti 2 AlC x ( x =0.69) with rich lattice defects . Notably, when stoichiometric powder mixtures were used as raw materials in combustion synthesis (SHS) the main phase of the derived products was Ti 3 AlC 2 with some Ti 2 AlC .…”

“…Notably, when stoichiometric powder mixtures were used as raw materials in combustion synthesis (SHS) the main phase of the derived products was Ti 3 AlC 2 with some Ti 2 AlC . The measured mean grain diameter is 3.05 μm, as determined by the planimetric method (ASTM‐E, 112‐1996) . Phase analysis by X‐ray diffraction (XRD; D/max‐rB, Japan) using Cu K α radiation with a step of 0.02° showed that Ti 2 AlC was present with TiAl in minor amounts.…”

“…In a previous work, our group succeeded in the synthesis and characterization of high‐purity Ti 2 AlC bulk by use of self‐propagating high‐temperature combustion synthesis with pseudo hot isostatic pressing (SHS/PHIP), with the advantages of low cost, very short synthesis times, simultaneous synthesis and densification. Importantly, the derived Ti 2 AlC exhibits excellent mechanical properties with a flexural strength of 606±20 MPa, due to the fine grains with a mean grain diameter of 3.05 μm . Following our previous work and in response to the great potential of Ti 2 AlC in high‐temperature applications, the aim of the present paper is to investigate the thermal shock behavior of Ti 2 AlC fabricated by the SHS/PHIP process, emphasizing the effect of the quenching temperature and quenching times.…”

Microstructure evolution and brazing mechanisms of the Ti2AlC/Ni joints using nickel based filler alloy

“…Although numbers of studies have been carried out on the synthesis of Ti 2 AlC [9][10][11], still it is difficult to fabricate bulk Ti 2 AlC with big dimensions and complex shapes in practice due to the narrow phase range in the Ti-Al-C ternary phase diagram [12], which severely hampers its widespread application. Joining technology is a convenient and effective approach to overcome this problem, being essential to the widespread application of the Ti 2 AlC ceramics in many fields [13].…”