Study of the Thermal Stability and Mechanical Characteristics of MAX Phases of Ti-Al-C(N) System and their Solid Solutions

Abstract

The DTA and TG study in air of Ti2Al (C1-xNx) and Ti3AlC2 synthesized under Ar 0.1 MPa pressure and densified in thermobaric conditions at 2 GPa, 1400 °C, for 1 h showed that the increase of the amount of TiC layers in Ti-Al-C MAX phases structures leads to the increase of their stability against oxidation: 321 MAX phase Ti3AlC2 are more stable than Ti2AlC and Ti2Al (C1-xNx) solid solutions both before and after thermobaric treatment. The oxide film formed on the surface of the highly dense (ρ=4.27 g/cm3, porosity 1 %) material based on nanolaminated MAX phase Ti3AlC2 (89 % Ti3AlC2, 6 % TiC, 5 % Al2O3) manufactured by hot pressing (at 30 MPa) made the material highly resistant in air at high temperatures: after 1000 hours of exposition at 600 °C it demonstrated a higher resistance to oxidation than chromium ferrite steels (Crofer GPU and JDA types). Due to the surface oxidation self-healing of defects took place. Besides, the Ti3AlC2 material demonstrated resistance against high-temperature creep and after being kept in H2 at 600 °C for 3h its bending strength reduced by 5 % only. At room temperature the Ti3AlC2 bulk exhibited microhardness Hμ = 4.6 GPa (at 5 N), hardness HV50 = 630 (at 50 N ) and HRA = 70 (at 600 N), Young modulus was 140 ± 29 GPa, bending strength =500 MPa, compression strength 700 MPa, and fracture toughness K1C=10.2 MPa·m0.5.

Presence of Oxygen in Ti-Al-C MAX Phases-Based Materials and their Stability in Oxidizing Environment at Elevated Temperatures

“…Besides, these materials are characterized by high electro-and thermal conductivities, low coefficients of friction and thermal expansion, resistance to radioactivity and oxidation. They also have self-healing properties [7][8][9][10][11][12][13]. Thus MAX-phase based materials are promising for application in different industries: power electrical, hydrogen, nuclear industries; aviation; space; mechanical and chemical engineering, etc.…”

“…Thus MAX-phase based materials are promising for application in different industries: power electrical, hydrogen, nuclear industries; aviation; space; mechanical and chemical engineering, etc. Recently Ti 3 AlC 2 -based materials have been proposed as interconnecting materials for hydrogen fuel cells, damping material for machining process and polishing powders for jewellery stones [12][13][14].…”

Behaviour of Solid Oxide Fuel Cell Materials in Technological Environments

“…This carbide belongs to so called MAX-phases which have a chemical formula: Mn+1AXn -where M is an early transition metal, A is an A-group element, and X is carbon and/or nitrogen. These materials have good thermal and electrical conductivity, low density, high strength and Young's modulus, excellent thermal shock resistance, high chemical resistance, relatively low thermal expansion coefficient and good machinability [7][8][9]. Owing to such combination of properties and small pores ( Fig.…”

Oxidation Resistance of Materials Based on Ti3AlC2 Nanolaminate at 600 °C in Air

“…The crystal structure of MAX phases can be described as octahedral ternary metal carbide and/or nitride sandwiched by close-packed layers of A-element. These materials have good thermal and electrical conductivity, low density, high strength and Young’s modulus, excellent thermal shock resistance, high chemical resistance, relatively low thermal expansion coefficient, and good machinability [1–3]. Owing to such combination of properties, they have been suggested for various applications, especially as high-temperature structural materials.…”