Mechanical alloying and field assisted hot pressing of nanocrystalline B2-NiAl intermetallic compound

Abstract

Ordered B2-NiAl intermetallic compound powder was successfully synthesised by mechanical alloying after 20 h in an attritor mill, starting from elemental Ni and Al powders and without subsequent heat treatment. NiAl powder obtained was homogenous and had a nanocrystalline microstructure. It was consolidated by field assisted hot pressing (FAHP), in a novel configuration with a Gleeble 3800 thermomechanical simulator. The powder was also processed by hot isostatic pressing (HIP) in order to compare both methods. The consolidation was successful by both methods obtaining above 98% of NiAl theoretical density (5?86 g cm -3 ). The results showed that the consolidation process by FAHP technique is effective and uniform throughout the sample as indicated by homogenous hardness values, obtaining microstructure and properties similar to those obtained with HIP technique, with certain advantages over it. The achieved room temperature yield strength of 850 MPa and fracture strain 26-28% corresponds to the bulk values of NiAl intermetallic.

Nickel Aluminide intermetallic composites fabricated by various processing routes – a review

“…Mashreghi and Moshksar performed the test on mechanically alloyed NiAl intermetallic. This work approached different milling times (19,30,45, and 55 h) with the BPR ratio of 20:1 and finally found the NiAl intermetallic peak at 19 h of MA. After sintering at 850°C, phase changes happened because of the gradual exothermic reaction mechanism.…”

“…The microhardness value (408 HV) has increased than the NiAl due to the solution hardening. The toughness value increased due to the ductility phase [45].

Figure 17 Solid-liquid interface at different withdrawal rate (a and a1) 6 µm/s (b and b1) 15 µm/s (c and c1) 30 µm/s (d and d1) 60 µm/s (e and e1) 120 µm/s [44].

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“…The microhardness value (408 HV) has increased than the NiAl due to the solution hardening. The toughness value increased due to the ductility phase [45].…”

Study of NiAl-based alloy parts produced by metal injection moulding

“…Although the service temperature of superalloys can meet the requirements, the high density (∼7.5-9.1 g cm −3 ) hinders the future development of lightweight aerospace engines [3,4]. Therefore, it is urgent to carry out research on new high-temperature materials and advanced manufacturing technology, in order to replace Ni-based superalloys and reduce the weight of key components for new-generated supersonic aircraft engines [5,6].…”