新聞資訊
熱循環作用下2A12鋁合金的微觀結構與性能
發布人：上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間：2015-08-18
為了考察低地球軌道衛星運行環境下金屬材料的冷熱疲勞損傷機制，采用模擬實驗，并利用光學顯微鏡、XRD、TEM 及顯微硬度儀分析研究熱循環作用下2A12鋁合金的微觀結構和性能的演化行為。
熱循環作用下2A12鋁合金的微觀結構與性能Microstructure and properties of 2A12 aluminum alloy under thermocycling
為了考察低地球軌道衛星運行環境下金屬材料的冷熱疲勞損傷機制，采用模擬實驗，并利用光學顯微鏡、XRD、TEM 及顯微硬度儀分析研究熱循環作用下2A12鋁合金的微觀結構和性能的演化行為。結果表明: 在200次以內的熱循環過程中，樣品硬度有所降低；200~300次循環樣品則出現循環硬化現象；300次循環后，樣品硬度迅速下降，出現循環軟化現象。微結構分析結果表明：熱循環過程中，2A12鋁合金的性能變化與其微觀結構的演化行為關系密切，300次熱循環時，樣品中形成了大量尺寸細小的針狀S′相(Al2CuMg)；而500次循環樣品中，S′相消失，代之以粗大S相(Al2CuMg)的形成。此外，500次熱循環后，析出相附近區域形成大量的空穴，這些空穴容易成為冷熱疲勞裂紋萌生的有利位置。
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.