Synthesis, properties and thermal decomposition of the Ta4AlC3 MAX phase

TL;DR

This paper reports a method to synthesize high-purity Ta4AlC3 MAX phase ceramics, characterizes their microstructure and mechanical properties, and investigates their thermal decomposition for potential porous tantalum carbide production.

Contribution

It introduces a synthesis route for high-purity Ta4AlC3 MAX phase ceramics and studies their properties and thermal decomposition behavior.

Findings

High-purity alfa-Ta4AlC3 achieved at 1500°C hot pressing.

Beta-Ta4AlC3 observed in SPS samples.

Thermal decomposition into tantalum carbide and Al vapor at 1200-1250°C.

Abstract

The present work describes a synthesis route for bulk Ta4AlC3 MAX phase ceramics with high phase purity. Pressure assisted densification was achieved by both hot pressing and spark plasma sintering of tantalum hydride, aluminium and carbon powder mixtures in the 1200-1650{\deg}C range. The phases present and microstructures were characterized as a function of the sintering temperature by X-ray diffraction and scanning electron microscopy. High-purity alfa-Ta4AlC3 was obtained by hot pressing at 1500{\deg}C for 30 min at 30 MPa. The beta-Ta4AlC3 allotrope was observed in the samples produced by SPS. The elastic modulus, Vickers hardness, flexural strength and single-edge V-notch beam fracture toughness of the high-purity bulk sample were determined. The thermal decomposition of Ta4AlC3 into tantalum carbide and Al vapor in high vacuum at 1200{\deg}C and 1250{\deg}C was also investigated, as a possible processing route to produce porous tantalum carbide components.