Effects of sample stoichiometry of thermite-based SHS reactions on formation of Nb–Al intermetallics

An investigation on formation of Nb2AlC by combustion synthesis of Nb2O5–Al–Al4C3 powder compacts

“…2, the flamefront velocity is considerably decreased from 12.4 to 8.2 mm/s by an increase in the proportion of Al from Nb 2 O 5 :Al:Al 4 C 3 = 3:9:1 to 3:13:1. This is most likely attributed to the reduced exothermicity of the SHS process resulting from more energy being consumed as the latent heat of Al when the content of Al increases [40].…”

“…As the first attempt, this study aims at preparation of Nb 2 AlC by combustion synthesis in the SHS mode from the powder mixture of Nb 2 O 5 , Al, and Al 4 C 3 . The purpose of adopting Nb 2 O 5 as the source of niobium is twofold: one is to take advantage of the large amount of heat liberated from the thermite reaction between Al and Nb 2 O 5 [39,40]; the other is to generate Al 2 O 3 as a reinforcement for Nb 2 AlC. The incorporation of Al 2 O 3 into the MAX carbides has been shown to improve their hardness, toughness, and strength [41,42].…”

Effect of holding time on the production of Nb-NbAl3 intermetallic composites via electric-current-activated sintering

“…[1][2][3] Three intermetallic compounds are present in the Nb-Al binary system including Nb 3 Al (A15 structure), Nb 2 Al (D8b structure) and NbAl 3 (DO22 structure, TiAl 3 type). [4][5][6][7] Among the various compounds in the Nb-Al system (Figure 1), NbAl 3 with its high melting point (1680°C), low density (4.54 g/cm 3 ), is attractive as a potential material for high-temperature applications. 6,8 The applications of NbAl 3 include its use in turbine blades in aircraft engines or in stationary gas turbines.…”

“…1,6,10 In-situ toughening is an alternative technique to enable a combination of brittle intermetallic phase with a ductile metallic phase in one step production. 11,12 Some conventional methods such as melting, casting and mechanical alloying techniques or self-propagating high-temperature synthesis (SHS) [7][8][9] developed electric current activated/assisted sintering (ECAS) technique has been used in this study. This system enables the cold formed compact obtained from uniaxial compression to be inserted into a container, which is heated by passing an electrical current.…”

Formation of Ta–Al intermetallics by combustion synthesis involving Al-based thermite reactions

“…For example, by means of the thermite-based SHS process with Al and Nb 2 O 5 as the reactants, Yeh and Wang [24] successfully fabricated two Nb-rich aluminides Nb 3 Al and Nb 2 Al, both of which cannot be formed through the reaction between Nb and Al particles due to weak exothermicity. Moreover, the integration of combustion synthesis with Al-based thermite reactions leads to in situ formation of the aluminide matrix composite reinforced by Al 2 O 3 [25][26][27].…”