Atomic-scale investigation of the heterogeneous precipitation in the E (Al18Mg3Cr2) dispersoid of 7075 aluminum alloy

The heterogeneous precipitation of the ? (MgZn2) phase on E (Al18Mg3Cr2) dispersoids 7075 aluminum alloy was systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive X-ray spectrometry (EDX). It is found that coarse particles are heterogeneously precipitated at particle interface after water quenching isothermal aging 120 °C. incoherent E/Al responsible for high tendency phase. Two different orientation relationships (ORs) between ?, Al matrix identified: OR1 [21¯1¯0]?//[011]E//[1¯12]Al, (011¯0)?//(133¯)E//(201)Al, OR2 [1¯12]E//[0001]?//[011]Al, (011¯0)?//(220)E//(344¯)Al. preferential to nucleate along {111}E or {220}E planes, depending its OR. nucleation could stabilize introducing a coherent E/? interface, which increases drive force precipitation. reorientation mutual diffusion solute atoms assist coherency interface. present results suggest increasing promising method suppress