“界面素化”策略改善铝基复合材料腐蚀性能

Plain interface strategy toward the high corrosion performance of Al matrix composites

添加增强相可以提高铝基复合材料的力学性能,但同时也会促进界面上原电池网络的形成,从而提升铝基复合材料的腐蚀敏感性.因此,优化界面结构是改善复合材料耐腐蚀性能的重要途径.对此,我们提出固相铝热反应结合热处理的策略,在Al-CuO复合材料中构建包括晶界和增强体-基体界面在内的“素化界面”.本文通过浸渍/电化学腐蚀试验和微观结构表征系统研究了复合材料的晶间腐蚀行为和应力腐蚀开裂敏感性,强调了晶内分布纳米第二相(Al_(2)O_(3)增强相和Al-Cu沉淀相)对消除沿晶界连续原电池网络和阻断腐蚀路径的贡献.此外,研究发现具有低应变能且紧密结合的Al_(2)O_(3)-Al界面显著降低了局部腐蚀敏感性.这项工作阐明了复合材料界面特性与腐蚀机制之间的相关性,为发展耐腐蚀复合材料提供了新思路.

Incorporating reinforcements can improve the mechanical properties of Al matrix composites but make them susceptible to corrosion attacks by facilitating the formation of a galvanic cell network along the interface.The optimiza-tion of the interfacial structure improves the corrosion re-sistance of the composites.Herein,a solid-state thermite reaction integrated with a heat treatment strategy was devel-oped to create plain interfaces,encompassing the grain boundary(GB)and reinforcement-matrix interface,in an Al-CuO composite system.The intergranular corrosion behavior and susceptibility to stress corrosion cracking of the compo-site were comprehensively examined by immersion/electro-chemical corrosion tests and microstructural characterizations.The intragranular distribution of nanosized secondary phases,i.e.,Al_(2)O_(3) and precipitates,was investigated to address their contribution to the continuous galvanic cell detachment along the GBs and interruption of the corrosion path,thus boosting the corrosion duration.In addition,the tightly bonded Al_(2)O_(3)-Al interface with low strain energy distinctly lowers local susceptibility to corrosion.This study illuminates the correlation between interface characteristics and corrosion mechanisms in the composites,which can shed light on the development of high-corrosion-resistant compo-sites.