Phase transitions induced in hcp M_n+1AX_n phases (Ti₂AlN, Ti₂AlC, and Ti₄AlN₃) by 1 MeV Au⁺ ion irradiation were investigated, over a series of ion fluences ranging from 1×10¹⁴ to 2×10¹⁶ ions cm^-2, by transmission electron microscopy (TEM) and synchrotron grazing incidence X-ray diffraction (GIXRD). Irradiation-induced structural evolutions were observed using high-resolution TEM (HRTEM) imaging and selected area electron diffraction (SAED). Based on phase contrast imaging and electron diffraction pattern (EDP) simulations, the atomic-scale mechanisms for the phase transitions were determined. Transformations of the initial hcp phases to the intermediate γ-phases and fcc phases were driven by the formation of Ti/Al antisite defects and extended stacking faults induced by ion irradiation. By comparing the transformation behavior of Ti₂AlN with that of Ti₂AlC and Ti₄AlN₃ under the same irradiation conditions, using both the experimental data and first-principles calculations, the role of the X and n parameters in the radiation responses of M_n+1AX_n phases were elucidated. The susceptibilities of materials in this Ti-Al-X (X=C, N) system to irradiation-induced phase transitions were determined with respect to the bonding characteristics and compositions of these MAX phases. Ti₂AlC is slightly less susceptible to the radiation-induced phase transformation than is Ti₂AlN, which is attributed to the stronger Ti-Al bond covalency in Ti₂AlN. Ti₄AlN₃ is more resistant to radiation-induced phase transformations than is Ti₂AlN, due to the lower Al content and lower anion vacancy ratio in the irradiation-induced solid solution phases.

研究了1 MeV Au ⁺离子辐照在hcp M _{n +1} AX _n相（Ti ₂ AlN，Ti ₂ AlC和Ti ₄ AlN ₃）中引起的相变，其离子通量范围为1×10 ¹⁴至20。 2×10 ¹⁶离子cm ^-2，通过透射电子显微镜（TEM）和同步辐射掠入射X射线衍射（GIXRD）。使用高分辨率TEM（HRTEM）成像和选择区域电子衍射（SAED）观察了辐照引起的结构演变。基于相衬成像和电子衍射图（EDP）模拟，确定了相变的原子尺度机理。初始hcp相向中间γ相和fcc相的转变是由Ti / Al反位缺陷的形成和离子辐照引起的扩展堆垛层错驱动的。通过比较Ti ₂ AlN与Ti ₂ AlC和Ti ₄ AlN ₃的转变行为在相同的照射条件下，使用实验数据和第一性原理计算，阐明了X和n参数在M _{n + 1} AX _n相的辐射响应中的作用。关于这些MAX相的结合特性和组成，确定了该Ti-Al-X（X = C，N）系统中材料对辐射诱导的相变的敏感性。的Ti ₂ ALC是对辐射诱导的相变略小于敏感是钛₂的AlN，这归因于在钛更强的Ti-Al键共价₂的AlN。Ti ₄ AlN ₃由于在辐射诱导的固溶体相中较低的Al含量和较低的阴离子空位比，因此与Ti ₂ AlN相比，它对辐射诱导的相变具有更强的抵抗力。