CAJ | 학술논문

　　对固溶–淬火处理后的 Al-3.7Cu-1.6Mg 合金板材进行变形量分别为0、5%和10%的预拉伸处理，然后置于空气中进行自然时效，研究预变形对 Al-3.7Cu-1.6Mg 合金自然时效态的硬度、室温拉伸性能和断裂韧性的影响，利用扫描电镜(SEM)与透射电镜(TEM)观察合金的显微组织及断口形貌，研究其断裂机理。结果表明：该合金在淬火后引入预拉伸变形，可显著提高其自然时效态的硬度和屈服强度，同时抑制 GPB 区的形成，降低时效析出速率，并使峰时效时间延长；随预变形量从0增加至10%，Al-3.7Cu-1.6Mg 合金的断裂韧性降低，这主要是预变形增加了基体内的位错密度，位错切割细小的 GPB 区粒子，大量滑移被抵消，造成变形过程中局部应力集中，从而形成微裂纹；由断口分析可知该合金的断裂类型为穿晶韧窝型断裂，且随预变形程度增大，韧窝直径和深度均增大。
　　대고용–쉬화처리후적 Al-3.7Cu-1.6Mg 합금판재진행변형량분별위0、5%화10%적예랍신처리，연후치우공기중진행자연시효，연구예변형대 Al-3.7Cu-1.6Mg 합금자연시효태적경도、실온랍신성능화단렬인성적영향，이용소묘전경(SEM)여투사전경(TEM)관찰합금적현미조직급단구형모，연구기단렬궤리。결과표명：해합금재쉬화후인입예랍신변형，가현저제고기자연시효태적경도화굴복강도，동시억제 GPB 구적형성，강저시효석출속솔，병사봉시효시간연장；수예변형량종0증가지10%，Al-3.7Cu-1.6Mg 합금적단렬인성강저，저주요시예변형증가료기체내적위착밀도，위착절할세소적 GPB 구입자，대량활이피저소，조성변형과정중국부응력집중，종이형성미렬문；유단구분석가지해합금적단렬류형위천정인와형단렬，차수예변형정도증대，인와직경화심도균증대。
The effect of pre-stretching on the hardness, tensile property and fracture toughness of Al-3.7Cu-1.6Mg alloy was investigated using scanning electron microscopy, transmission electron microscopy, hardness test, tensile test and fracture toughness test. Results indicate that the pre-stretching significantly increases the ‘natural aging’ hardness and the yield strength of the Al-3.7Cu-1.6Mg alloy. Meanwhile, the suppression of the formation of GPB zones by pre-stretching results in decreasing aging precipitation rate and prolonging the time to reach peak aging condition. The fracture toughness decreases when the pre-stretching increases from 0 to 10%. This is attributed to the fact that the interaction between the dislocations and the fine GPB zone particles is intensified by the increasing of pre-stretching, leading to large local strain concentrations and facilitating the formation of the micro-cracks. Furthermore, the decrease of the plasticity is detrimental to the crack propagation resistance and leads to the lower fracture toughness. The fracture surface observation showed that the alloy possesses a ductile transgranular character. Also, both the diameter and the depth of the dimples increase with the increasing of pre-stretching.