Synthesis and Characterization of a Nearly Single Bulk Ti2AlN MAX Phase Obtained from Ti/AlN Powder Mixture through Spark Plasma Sintering.

Christopher Salvo,Cristina García-Garrido,Ernesto Chicardi,Cristina López-Pernía,José Antonio Jiménez,Ramalinga Viswanathan Mangalaraja,Rosalía Poyato,Pablo Tobosque

doi:10.3390/ma14092217

Abstract

MAX phases are an advanced class of ceramics based on ternary carbides or nitrides that combine some of the ceramic and metallic properties, which make them potential candidate materials for many engineering applications under severe conditions. The present work reports the successful synthesis of nearly single bulk Ti2AlN MAX phase (>98% purity) through solid-state reaction and from a Ti and AlN powder mixture in a molar ratio of 2:1 as starting materials. The mixture of Ti and AlN powders was subjected to reactive spark plasma sintering (SPS) under 30 MPa at 1200 °C and 1300 °C for 10 min in a vacuum atmosphere. It was found that the massive formation of Al2O3 particles at the grain boundaries during sintering inhibits the development of the Ti2AlN MAX phase in the outer zone of the samples. The effect of sintering temperature on the microstructure and mechanical properties of the Ti2AlN MAX phase was investigated and discussed.

Highlights

MAX phases are a relatively new class of advanced ceramics that adopted this name due to the general formula that describes them, Mn+1 AXn, where n = 1, 2, or 3, M is an early transition metal, A is an IIIA/IVA-group element and X is C and/or N. These ternary carbides or nitrides combine some of the properties of ceramics and metals, exhibiting high electrical and thermal conductivities, good thermal shock resistance, superior oxidation/corrosion resistance and ease of machining [1,2]. These combined properties, which emanate from their atomic bonding and the nature of the crystalline structure, make them potential candidate materials to be used in advanced technological applications under severe conditions, such as high temperature, aggressive corrosion environment, and high irradiation in aerospace or nuclear systems [3,4,5]
MAX phases have a layered hexagonal crystal structure with P63/mmc space group symmetry, which consists of alternative near close-packed layers of M6 X octahedral and the layers of A atoms located at the center of the trigonal prisms [3]
The observation of particle morphology of the raw powders and the Ti:AlN powders mixture was carried out using a JEOL scanning electron microscope (SEM) model JSM-6380LV 9 (JEOL, Peabody, mechanical alloying (MA), USA)

Summary

Introduction

MAX phases are a relatively new class of advanced ceramics that adopted this name due to the general formula that describes them, Mn+1 AXn , where n = 1, 2, or 3, M is an early transition metal, A is an IIIA/IVA-group element and X is C and/or N. These ternary carbides or nitrides combine some of the properties of ceramics and metals, exhibiting high electrical and thermal conductivities, good thermal shock resistance, superior oxidation/corrosion resistance and ease of machining [1,2]. More than 155 MAX phases have been reported [7], the MAX phases based on the Ti-Al-N and

Methods

Results

Conclusion