【摘要】 AZ91D合金中加入1%La（质量分数）后,不但形成了条状的Al₁₁La₃相和块状的Al₈LaMn₄相,而且在粗大β相(Mg₁₇Al₁₂)周围形成了许多细小的层片状β相,并使β相进一步网状化.这些细小的层片状β相明显阻碍了腐蚀的扩展,提高了AZ91D镁合金的耐蚀性.条状的Al₁₁La₃相和块状的Al₈LaMn₄相都属于阴极耐蚀相.其中Al₁₁La₃相由于较小的阴极面积,对加速其周围镁基体的腐蚀不起明显作用;而块状的Al₈LaMn₄相阴极面积较大,与基体构成微电偶腐蚀,加速了基体的腐蚀.更多还原

【Abstract】 The microstructure,corrosion morphology and corrosion product of AZ91D and AZ91D-1.0La alloys were investigated.With the addition of 1%La（mass fraction）in AZ91D,not only rod-like Al₁₁La₃ and blocky Al₈LaMn₄ phases,but also much fine laminarβphase(Mg₁₇Al₁₂) around bulkβphase formed.The fine laminarβphase obviously restrained the further development of corrosion,which greatly improved the corrosion resistance of AZ91D.Al₁₁La₃ phase is cathodic phase,but this phase did not accelerate corrosion ofα-Mg matrix because rod-like Al₁₁La₃ only offers a small cathodic area.However,blocky Al₈LaMn₄ phase obviously accelerated corrosion ofα-Mg matrix because of its large cathodic area.更多还原