New MAX phases Ti₂(Al_xCu_1−x)N and Nb₂CuC were synthesized by A-site replacement by reacting Ti₂AlN and Nb₂AlC, respectively, with CuCl₂ or CuI molten salt. X-ray diffraction, scanning electron microscopy, and atomically resolved scanning transmission electron microscopy showed complete A-site replacement in Nb₂AlC, which lead to the formation of Nb₂CuC. However, the replacement of Al in Ti₂AlN phase was only close to complete at Ti₂(Al_0.1Cu_0.9)N. Density-functional theory calculations corroborated the structural stability of Nb₂CuC and Ti₂CuN phases. Moreover, the calculated cleavage energy in these Cu-containing MAX phases are weaker than in their Al-containing counterparts.

通过分别通过使Ti ₂ AlN和Nb ₂ AlC与CuCl ₂或CuI熔融盐反应进行A位置换来合成新的MAX相Ti ₂（Al _x Cu _{1- x}）N和Nb ₂ CuC 。X射线衍射，扫描电子显微镜和原子分辨扫描透射电子显微镜显示Nb ₂ AlC中的A位完全取代，这导致Nb ₂ CuC的形成。但是，Ti ₂ AlN相中的Al置换仅在Ti ₂处接近完成（Al _0.1 Cu _0.9N. 密度泛函理论计算证实了Nb ₂ CuC和Ti ₂ CuN相的结构稳定性。而且，在这些含Cu的MAX相中计算出的裂解能比在其含Al的相中弱。