Compatibility of $Z{r}_{2}AlC$ MAX phase-based ceramics with oxygen-poor, static liquid lead-bismuth eutectic

This work investigates the compatibility of $Z{r}_{2}AlC$ MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local $Z{r}_{2}AlC$/LBE interaction. The ceramics were exposed to oxygen-poor ($C_O\le 2.2\cdot {10}^{-10}$ mass%), static liquid LBE at 500{\deg}C for 1000 h. A new $Z{r}_2(Al,Bi,Pb)C$ MAX phase solid solution formed in-situ in the LBE-affected $Z{r}_{2}AlC$ grains. Out-of-plane ordering was favorable in the new solid solution, whereby $\mathit{\text{A}}$-layers with high and low-Bi/Pb contents alternated in the crystal structure, in agreement with first-principles calculations. Bulk $Z{r}_2(Al,Bi,Pb)C$ was synthesized by reactive hot pressing to study the crystal structure of the solid solution by neutron diffraction.