Pulse Plasma Sintering of NiAl-Al2O3 Composite Powder Produced by Mechanical Alloying with Contribution of Nanometric Al2O3 Powder

Abstract

NiAl-Al2O3 composites, fabricated from the prepared composite powders by mechanical alloying and then consolidated by pulse plasma sintering, were presented. The use of nanometric alumina powder for reinforcement of a synthetized intermetallic matrix was the innovative concept of this work. Moreover, this is the first reported attempt to use the Pulse Plasma Sintering (PPS) method to consolidate composite powder with the contribution of nanometric alumina powder. The composite powders consisting of the intermetallic phase NiAl and Al2O3 were prepared by mechanical alloying from powder mixtures containing Ni-50at.%Al with the contribution of 10 wt.% or 20 wt.% nanometric aluminum oxide. A nanocrystalline NiAl matrix was formed, with uniformly distributed Al2O3 inclusions as reinforcement. The PPS method successfully consolidated NiAl-Al2O3 composite powders with limited grain growth in the NiAl matrix. The appropriate sintering temperature for composite powder was selected based on analysis of the grain growth and hardness of Al2O3 subjected to PPS consolidation at various temperatures. As a result of these tests, sintering of the NiAl-Al2O3 powders was carried out at temperatures of 1200 °C, 1300 °C, and 1400 °C. The microstructure and properties of the initial powders, composite powders, and consolidated bulk composite materials were characterized by SEM, EDS, XRD, density, and hardness measurements. The hardness of the ultrafine-grained NiAl-Al2O3 composites obtained via PPS depends on the Al2O3 content in the composite, as well as the sintering temperature applied. The highest values of the hardness of the composites were obtained after sintering at the lowest temperature (1200 °C), reaching 7.2 ± 0.29 GPa and 8.4 ± 0.07 GPa for 10 wt.% Al2O3 and 20 wt.% Al2O3, respectively, and exceeding the hardness values reported in the literature. From a technological point of view, the possibility to use sintering temperatures as low as 1200 °C is crucial for the production of fully dense, ultrafine-grained composites with high hardness.

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

“…Based on the histogram, it was found that the actual size of the powders was close to the manufacturer's stated size. Similar conclusions were obtained in previous work [17,28]. The SEM images of the metal powders are shown in Figure 4.…”

“…The results of our own previously prepared works were concentrated on the preparation and characterization of NiAl-Al 2 O 3 composite powder. The composite powder was prepared by mechanical alloying from powder mixtures containing Ni-50 at.% and Al with a contribution of 10 wt.% or 20 wt.% of Al 2 O 3 [17]. However, positive attempts to use more than-30 wt.% Al 2 O 3 were also made.…”

“…The results revealed that the composite powder could be used to reinforce ceramics and to fabricate CMCs with complex microstructures [17]. In such composites, new phases, such as spinel NiAl 2 O 4 , can also be formed during air sintering.…”

Effect of Copper on Microstructure and Performance of WC/NiAl/TiC Composite Coatings by Laser Cladding

“…[ 2 ] The composite design for cladding process focuses on low‐cost together with high‐performance material characteristics. The NiAl‐based material is prepared and investigated to develop various applications, including directed solidification, [ 3 ] casting, [ 4 ] mechanical alloying methods, [ 5 ] and additive manufacturing. [ 6 ]…”

“…[2] The composite design for cladding process focuses on low-cost together with highperformance material characteristics. The NiAl-based material is prepared and investigated to develop various applications, including directed solidification, [3] casting, [4] mechanical alloying methods, [5] and additive manufacturing. [6] The intermetallic compounds of NiAl are characterized by a B2 crystal structure and exhibit a combination of capabilities derived from both metallic and ceramic materials.…”