析出相对Al-Cu-Mg合金蠕变行为的影响

摘要

Alloys at four different heat treatment states (T4, underaged, peakaged and overaged) were prepared, and their creep behaviors under the conditions of 150 ℃, 225 MPa and 200 ℃, 200 MPa were studied through constant-stress tensile creep experiments and microstructure observations. The results indicate that, when crept at 150 ℃, the deformation of alloys mainly depends on the dislocation slip within the grains. The pinning effect of dispersed tiny precipitates and solutes on the dislocations can decrease the creep rate of alloys effectively. All four alloys experience a long term steady creep stage and the peakaged state alloy possesses the lowest creep rate. When crept at 200 ℃, the main deformation of alloys switches to grain boundary (GB) sliding. Precipitate-free zones (PFZs) form in the peakaged and overaged state alloys during creeping, which increases the creep rate of alloys remarkably and disappears the steady creep stage of these alloys. The underaged state alloy possesses the lowest creep rate at this creep condition.%利用不同的热处理制度制备T4、欠时效、峰时效和过时效4种状态的合金，并通过恒应力蠕变拉伸实验和显微组织观察分别对不同状态合金在150℃、225 MPa和200℃、200MPa的蠕变行为进行分析。结果表明：合金在150℃蠕变时，变形主要依靠晶内的位错滑移，细小弥散分布的析出相以及固溶原子对位错的钉扎有利于降低合金的蠕变速率；4种合金在该蠕变条件下均经历较长的稳态蠕变阶段，其中峰时效合金的蠕变速率最低；合金在200℃蠕变时，变形主要依靠晶界滑移；在蠕变过程中，峰时效态和过时效态合金中形成明显的无沉淀析出带，导致其蠕变速率显著增加，并且几乎没有出现明显的稳态蠕变阶段；欠时效态合金在该蠕变条件下的蠕变速率最低。