Synthesis and physical properties of (Zr_1−x,Ti_x)₃AlC₂MAX phases

Abstract

MAX phase solid solutions physical and mechanical properties may be tuned via changes in composition, giving them a range of possible technical applications. In the present study, we extend the MAX phase family by synthesizing (Zr 1Àx Ti x ) 3 AlC 2 quaternary MAX phases and investigating their mechanical properties using density functional theory (DFT). The experimentally determined lattice parameters are in good agreement with the lattice parameters derived by DFT and deviate <0.5% from Vegard's law. Ti 3 AlC 2 has a higher Vickers hardness as compared to Zr 3 AlC 2 , in agreement with the available experimental data. The first (n=1) and second (n=2) members of the family are known as the 211 and 312 MAX phases respectively. A feature of them is the highly symmetric unit cell with atomic layers stacked along the c-direction. Numerous MAX phases were synthesized that shared these metallic and ceramic properties (good machinability, high melting temperature, high thermal shock resistance, high elastic stiffness, high thermal, and electrical conductivity), effectively motivating their technological application. [2][3][4][5] The key for the metallic and ceramic properties is the structure that consists of the stacking of M n+1 X n "ceramic" layer(s) interleaved by an A "metallic" layer. 2-5Ti-based MAX phases such as Ti 3 AlC 2 are of significant technical interest as they have excellent properties combined with a strong oxidation resistance in air due to formation of a passivating Al 2 O 3 outer layer.6 Related MAX phases have been investigated as candidate materials for passive safety protection of nuclear fuel cladding

Structural and optical properties of the recently synthesized (Zr3−x Ti x )AlC2 MAX phases

“…The lattice parameters are in excellent agreement with the recently determined results [32]. The Fermi surfaces consist of low-dispersive transition metal d-like bands, which play a vital role for the conductivity in the compounds.…”

“…Therefore, the solid solutions (Zr 3-x Ti x )AlC 2 , mixing of Zr and Ti, should have properties better than that of many other MAX phases. Motivated by this, Zapata-Solvas et al [32], very recently, successfully synthesized (Zr 3-x Ti x )AlC 2 MAX phases and calculated some physical properties with different x content. Here, we investigate the complementary structural and optical properties of (Zr 3-x Ti x )AlC 2 using density functional theory (DFT).…”

The Stability of Irradiation-Induced Defects in Zr ₃AlC ₂, Nb ₄AlC ₃ and (Zr _0.5,Ti _0.5) ₃AlC ₂ Max Phase-Based Ceramics

“…It is believed that the N 2 purge used during the experiment led to the destabilisation of the Zr 3 AlC 2 MAX phase. The addition of Ti to the (Zr 0.5 ,Ti 0.5 ) 3 AlC 2 led to the stabilisation of the MAX phase, as demonstrated during its synthesis [15] , preventing its decomposition. Therefore, part of the plateauing effect observed in the c -parameters of both AR and irradiated Zr 3 AlC 2 ( Fig.…”

“…New MAX phase compounds, with an M element of Zr, Nb and/or Ti, have been fabricated as potential fuel cladding coating materials either for ATF applications (LWRs), or for next-generation nuclear systems with corrosive primary coolants (e.g. Gen-IV leadcooled fast reactors, LFRs) [11][12][13][14][15] . Zr-based MAX phases are of particular interest due to the small neutron cross-section of Zr and the promising performance of ZrC-based ceramics in nuclear environments [16 , 17] .…”

“…Previous studies into the irradiation-response of MAX phase-based ceramics have focussed almost exclusively on Ti-based compounds [5 , 7 , 18-26] . Dual Zr/Ti MAX phase solid solutions are attractive due to the reduction of the material neutron cross-section through the partial replacement of Ti by Zr [15] . Proton ( H + ) irradiation of these ceramics has been carried out to two specific damage levels allowing an assessment of the lattice response of each material to these irradiations.…”