Synthesis and Characterization of Double Solid Solution (Zr,Ti)₂(Al,Sn)C MAX Phase Ceramics

Abstract

Quasi phase-pure (>98 wt %) MAX phase solid solution ceramics with the (Zr,Ti)2(Al0.5,Sn0.5)C stoichiometry and variable Zr/Ti ratios were synthesized by both reactive hot pressing and pressureless sintering of ZrH2, TiH2, Al, Sn, and C powder mixtures. The influence of the different processing parameters, such as applied pressure and sintering atmosphere, on phase purity and microstructure of the produced ceramics was investigated. The addition of Sn to the (Zr,Ti)2AlC system was the key to achieve phase purity. Its effect on the crystal structure of a 211-type MAX phase was assessed by calculating the distortions of the octahedral M6C and trigonal M6A prisms due to steric effects. The M6A prismatic distortion values were found to be smaller in Sn-containing double solid solutions than in the (Zr,Ti)2AlC MAX phases. The coefficients of thermal expansion along the ⟨a⟩ and ⟨c⟩ directions were measured by means of Rietveld refinement of high-temperature synchrotron X-ray diffraction data of (Zr1–x ,Ti x )2(Al0.5,Sn0.5)C MAX phase solid solutions with x = 0, 0.3, 0.7, and 1. The thermal expansion coefficient data of the Ti2(Al0.5,Sn0.5)C solid solution were compared with those of the Ti2AlC and Ti2SnC ternary compounds. The thermal expansion anisotropy increased in the (Zr,Ti)2(Al0.5,Sn0.5)C double solid solution MAX phases as compared to the Zr2(Al0.5,Sn0.5)C and Ti2(Al0.5,Sn0.5)C end-members.

Ta-based 413 and 211 MAX phase solid solutions with Hf and Nb

“…1). In order to increase the amount of the 413 MAX phase, 50% of the Al content was substituted for Sn, in analogy with prior studies on the synthesis of phase-pure (Zr,Nb)2(Al,Sn)C [41] and (Zr,Ti)2(Al,Sn)C [20] MAX phase ceramics. In those studies, the enhanced stability of the 211 MAX phases over the competing binary phases (carbides, intermetallics) was associated with the trigonal prism distortion parameter and the relative size of the M and A atoms in the M6A prism [42].…”

“…Moreover, the synthesis of (Ta1-x,Hfx)4(Al0.5,Sn0.5)C3 and (Ta1-x,Nbx)4(Al0.5,Sn0.5)C3 double solid solutions was explored in an attempt to produce MAX phase-based bulk ceramics with higher phase purity. This approach has already been successfully implemented in the synthesis of double solid solution (Zr,Nb)2(Al,Sn)C and (Zr,Ti)2(Al,Sn)C MAX phase ceramics [19,20].…”

Processing of MAX phases: From synthesis to applications

“…PLS is one of the most common synthesis methods due to its simplicity. 145,147,148,149,150,151 The pellets are just placed in a crucible and heated under vacuum or argon atmosphere to temperatures around 1400°C for few hours. The formation of MAX phases starts around 1000°C, but the highest yield is achieved around 1300°C-1400°C.…”

“…PLS is one of the most common synthesis methods due to its simplicity 145,147,148,149,150,151 . The pellets are just placed in a crucible and heated under vacuum or argon atmosphere to temperatures around 1400°C for few hours.…”

WITHDRAWN: Temperature-influenced Substitution of Si in Ti3(Si,Al)C2  Solid Solution

“…Solid solution modi cation method was often used to transform ternary MAX phase to quaternary, or even quinary compounds which at least contain two M, two A or two X elements, such as (Cr,Ti) 3 AlC 2 [13], (Zr,Ti) 3 AlC 2 [14], Ti 2 (Al,Sn)C [15], (Ti,Cu) 3 (Al,Cu)C 2 [16], (Zr,Ti) 2 (Al,Sn)C [17]. Burr [13] summarized the major advantages of quaternary MAX ceramics, indicating that they had new and outstanding mechanical properties compared with common MAX phases.…”