CAJ | 학술논문

为了考察低地球轨道卫星运行环境下金属材料的冷热疲劳损伤机制,采用模拟实验,并利用光学显微镜、XRD、TEM 及显微硬度仪分析研究热循环作用下2A12铝合金的微观结构和性能的演化行为.结果表明:在200次以内的热循环过程中,样品硬度有所降低;200~300次循环样品则出现循环硬化现象;300次循环后,样品硬度迅速下降,出现循环软化现象.微结构分析结果表明:热循环过程中,2A12铝合金的性能变化与其微观结构的演化行为关系密切,300次热循环时,样品中形成了大量尺寸细小的针状 S′相(Al2CuMg);而500次循环样品中, S′相消失,代之以粗大 S 相(Al2CuMg)的形成.此外,500次热循环后,析出相附近区域形成大量的空穴,这些空穴容易成为冷热疲劳裂纹萌生的有利位置.
위료고찰저지구궤도위성운행배경하금속재료적랭열피로손상궤제,채용모의실험,병이용광학현미경、XRD、TEM 급현미경도의분석연구열순배작용하2A12려합금적미관결구화성능적연화행위.결과표명:재200차이내적열순배과정중,양품경도유소강저;200~300차순배양품칙출현순배경화현상;300차순배후,양품경도신속하강,출현순배연화현상.미결구분석결과표명:열순배과정중,2A12려합금적성능변화여기미관결구적연화행위관계밀절,300차열순배시,양품중형성료대량척촌세소적침상 S′상(Al2CuMg);이500차순배양품중, S′상소실,대지이조대 S 상(Al2CuMg)적형성.차외,500차열순배후,석출상부근구역형성대량적공혈,저사공혈용역성위랭열피로렬문맹생적유리위치.
@@@@The fatigue damage mechanisms of metal material under the satellite operation condition of low earth orbit environment were investigated. Optical microscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and microhardness tester were used to investigate the evolution behavior of microstructures and properties of 2A12 aluminum alloy under various thermal cycles. The results indicate that the hardness decreases a little within 200 cycles, and the cyclic hardening phenomenon appears in the 200?300 cycles. After 300 cycles, the hardness of sample decreases evidently, the cyclic softening phenomenon turns up. The changes of performances of 2A12 aluminum alloy during the thermocycling process are closely related to the microstructural evolution. There are a lot of needle-like S′ phases (Al2CuMg) with small sizes in the samples after 300 thermal cycles. Up to 500 cycles, the S′ phases disappear, and bulky S phases (Al2CuMg) form. In addition, a large number of the cavities appear near the precipitates. The cavities are likely to become the favorable positions for the initiation of fatigue cracks.