摘要
根据挤压镁合金AZ80人工时效热处理(T5-177℃,16 h)前后分别在空气和NaCl介质中的疲劳寿命,研究了变形镁合金的腐蚀疲劳机理以及β相在腐蚀疲劳中的作用.结果表明:时效可导致AZ80组织β相体积分数增加、拉伸强度和硬度提高,可明显地提高在低应力水平下的腐蚀疲劳寿命.在空气中,疲劳裂纹萌生于表层和亚表面中的夹杂物;而在腐蚀介质中,腐蚀疲劳微裂纹萌生于试样表面的腐蚀坑,点蚀坑萌生于与β相相邻的α相.疲劳断口可见河流花样、二次裂纹、韧窝,具有解理特征.阳极溶解是挤压镁合金AZ80的腐蚀疲劳机制.
The fatigue life of as-extruded magnesium alloy AZ80 in air and NaCl aqueous solution was measured. The mechanism of corrosion fatigue of extruded magnesium alloys and the roles of β phase were investigated. The results show that ageing can lead to the increase of the volume fraction of β phase and tensile strength and hardness of AZ80, and improve remarkably the fatigue life in corrosive media at lower stress level. Fatigue crack initiated at inclusions on the surface or subsurface of samples, while emanated at the corrosion pits, which induced microscopic cracks in corrosive solutions. The corrosion pits initiated at α-Mg matrix in the verge of β particles. Riverlet pattern, secondary cracks and dimples were visible on the fracture surfaces. The fracture morphology was of cleavage character. Stress-assisted dissolution (SAD) was the main mechanism of corrosion fatigue for extruded magnesium alloy AZ80.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2004年第6期561-567,共7页
Chinese Journal of Materials Research
基金
国家八六三计划新材料领域2001AA331050资助项目.
关键词
材料失效与保护
变形镁合金AZ80
腐蚀疲劳
机理
Corrosion fatigue
Cracks
Dissolution
Morphology
Solutions
Tensile strength
Volume fraction
Wrought iron
