铝锂合金8090+Ce的疲劳断裂特征

 研究了铝锂合金8090+Ce的疲劳寿命和断裂特征,并与2024铝合金相对比。结果表明,铝锂合金8090+Ce各应力水平的疲劳寿命均低于2024铝合金;其早期沿晶萌生的微小裂纹一般沿晶纵向扩展,而发展成为非扩展短裂纹,不构成对疲劳寿命的危害;其主断裂面上的短裂纹沿粗滑移带扩展,显示宽而平直的典型脆性疲劳条带;其瞬断方式为穿晶粗滑移带开裂+穿晶和沿晶撕裂的混合型,对应于较小的失稳扩展临界尺寸。

FATIGUE FRACTURE FEATURE OF ALUMINUM-LITHIUM ALLOY 8090+Ce

The fatigue life of aluminum-lithium alloy 8090+Ce is investigated, and compared with traditional aluminum alloy 2024. Specific emphasis is placed on researching the fracture feature of fatigue crack initiation, short crack growth and stable-loss growth for aluminum-lithium alloy 8090+Ce. The fatigue life of aluminum-lithium alloy 8090+Ce is inferior to that of traditional aluminium alloy 2024. The microcracks in grain boundaries are intergranular growth in longitude, and finally enter in non-growth condition. The growth mode of short cracks associating with the main fracture surface for this alloy is transgranular along coarse slip bands. The brittle fatigue strips, which are wider and straighter, are exhibited. The final fracture mode is transgranular along coarse slip bands together with transgranular and intergranular tear.