Effect of milling time on mechanical properties of Al₂O₃–NiAl composites

Abstract

of using Al 2 O 3 -NiAl composites at high temperature is therefore high. In the present study, Al 2 O 3 -NiAl composites Alumina-NiAl composites were prepared by powder were prepared using a straightforward powder metallurgy metallurgy processing for the evaluation of mechanical process and the effect of milling time on the mechanical properties as a function of composite composition. Fine properties investigated. alumina powder and coarse angular NiAl particles were attrition milled for diVerent time periods, using zirconia grinding media, resulting in the NiAl particles EXPERIMENTAL PROCEDURESbeing squeezed into elongated flakes. Dense composites Alumina powder (TM-DR, mean size=0•2 mm, Taimei were prepared by hot pressing in graphite dies at Chemical Co., Tokyo, Japan) and various amounts of nickel 1450°C and samples prepared for microstructure and aluminide powder (NiAl, mean size=5•9 mm, Xform Inc., properties characterisation. Increase in milling time New York, USA) were milled together in ethyl alcohol in was found to increase the aspect ratio of the NiAl an attritor (model 01-HD, Union Process Inc., USA) for 1 flakes which aligned perpendicular to the hot pressing or 12 h using zirconia balls (5 mm dia.) as grinding media direction during fabrication. T he strength and toughand a shaft rotation speed of 300 rpm. ness of the composites were found to be higher thanTo observe the morphology of the NiAl particles in the predicted by the rule of mixtures and this is ascribed Al 2 O 3 -NiAl powder mixtures after milling, the mixtures both to the bridging eVect of NiAl flakes between crack were first ultrasonically treated in water and the suspension surfaces, which is enhanced by the increased aspect of the slurry discarded to remove the fine Al 2 O 3 particles. ratio from increased milling time, and microstructural Most of the Al 2 O 3 particles could be removed after several refinement f rom grain growth inhibition.BCT /395 successive washings and the NiAl particles were collected for observation by scanning electron microscopy (SEM).

Elastic behaviour of a model two-phase material

“…The NiAl particles were elongated during the mixing process. 16 The aspect ratio of the NiAl particles in the sintered composites varied from 3 to 5. weakly bonded together, 15 no reaction interphase at the interface was observed.…”

Elastic properties of Al2O3–NiAl: a modified version of Hashin–Shtrikman bounds

“…The fracture toughness is thus enhanced. The NiAl particles were elongated during the mixing process [22]. The NiAl particles in the Al 2 O 3 -10 % NiAl composite are separated from each other.…”

Characterization of Al2O3 Matrix Composites Fabricated via the Slip Casting Method Using NiAl-Al2O3 Composite Powder

“…Although the final analyzed composites did not have a NiAl phase, the results can be compared to those of works on Al2O3-NiAl composites. Both in the work by Tuan et al, where the effect of NiAl additive on the structural and mechanical properties of the Al2O3 matrix composites was studied, and also in the research carried out by the team of Davies et al [14][15][16], the addition of NiAl to the ceramic matrix in each of these…”

“…In this sense of improving the negative properties of NiAl, which was also present in this paper's composite powder, NiAl-Al 2 O 3 was used to prepare the final bulk composite, Al 2 O 3 -(NiAl-Al 2 O 3 ). However, composites of Al 2 O 3 -NiAl, but fabricated from Al 2 O 3 and NiAl, are also described in the literature [14][15][16]. Improvement of the fracture toughness of these materials is reported in [14][15][16].…”

“…However, composites of Al 2 O 3 -NiAl, but fabricated from Al 2 O 3 and NiAl, are also described in the literature [14][15][16]. Improvement of the fracture toughness of these materials is reported in [14][15][16]. In our concept, using the composite powder, NiAl-Al 2 O 3 , mixed with Al 2 O 3 and then consolidated provides the advantage of obtaining composites with microstructures that consist of a ceramic matrix and two-phase reinforcement-NiAl inside of which are distributed fine Al 2 O 3 particles.…”