  This work investigates the compatibility of $Zr_{2}AlC$ MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local $Zr_{2}AlC$/LBE interaction. The ceramics were exposed to oxygen-poor ($C_{O}\le2.2 \cdot10^{-10}$ mass%), static liquid LBE at 500{\deg}C for 1000 h. A new $Zr_{2}(Al,Bi,Pb)C$ MAX phase solid solution formed in-situ in the LBE-affected $Zr_{2}AlC$ grains. Out-of-plane ordering was favorable in the new solid solution, whereby $\textit{A}$-layers with high and low-Bi/Pb contents alternated in the crystal structure, in agreement with first-principles calculations. Bulk $Zr_{2}(Al,Bi,Pb)C$ was synthesized by reactive hot pressing to study the crystal structure of the solid solution by neutron diffraction. 
Compatibility of $Zr_{2}AlC$ MAX phase-based ceramics with oxygen-poor,   static liquid lead-bismuth eutectic