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A Comparative Study of the Feasibility of Cellular MAX Phase Preforms Formation by Microwave-Assisted SHS and SPS Techniques

Dmitruk A., Lagos M., Naplocha K., Egizabal P.

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 2

575--582

Two methods were evaluated in terms of manufacturing of MAX phase preforms characterized with open porosity: microwave-assisted self-propagating high-temperature synthesis (SHS) and spark plasma sintering (SPS). The main purpose of fabrication of such open-porous preforms is that they can be successfully applied as a reinforcement in metal matrix composite (MMC) materials. In order to simulate the most similar conditions to microwave-assisted SHS, the sintering time of SPS was significantly reduced and the pressure was maintained at a minimum value. The chosen approach allows these two methods to be compared in terms of structure homogeneity, complete reactive charge conversion and energy effectivity. Study was performed in Ti-Al-C system, in which the samples were compacted from elemental powders of Ti, Al, C in molar ratio of 2:1:1. Manufactured materials after syntheses were subjected to SEM, XRD and STEM analyses in order to investigate their microstructures and chemical compositions. As was concluded, only microwave-assisted SHS synthesis allows the creation of MAX phases in the studied system. SPS technique led only to the formation of intermetallic secondary phases. The fabrication of MAX phases’ foams by microwave-assisted SHS presents some interesting advantages compared to conventional manufacturing methods. This work presents the characterization of foams obtained by microwave-assisted SHS comparing the results with materials produced by SPS. The analysis of SPS products for different sintering temperatures provided the better insight into the synthesis of MAX phases, supporting the established mechanism. Dissimilarities in the heating mechanisms that lead to the differing synthesis products were also discussed.

Reaction synthesis and microstructure of Al-Ti preform for composite reinforcing

Naplocha K., Granat K.

Archives of Foundry Engineering

2008

Vol. 8, iss. 1 spec.

227--232

Production method of intermetallic porous perform for reinforcing of composite materials were elaborated. Mixture of aluminum and titanium powder was cold isostatically pressed (CIPed) and such produced cylindrical pill was ignited in microwave field. Obtained structures usually have open porosity what making them enables for pressure infiltration with molten metal. The investigations of the structure revealed uniform morphology and globular structure of Al-Ti compound which achieved much higher microhardness than substrates. Obtained perform can be widely used as the reinforcement to produce hybrid composite materials by the infiltration method. Aluminum casting alloys can be locally reinforced to improve hardness and resistance to oxidization at high temperature.