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对比分析了未变质和不同La含量变质的ZL205A合金在180、200和220℃的高温蠕变性能,探索了未变质和La变质ZL205A合金在不同温度和外加应力条件下的显微形貌演变,分析了La变质ZL205A合金的高温蠕变作用机制。结果表明,在相同蠕变温度和外加应力作用下,La变质ZL205A合金的稳态蠕变速率都要低于未变质ZL205A合金,且在La含量为0.3%时最低;经过La变质处理的ZL205A合金的表观应力指数都高于相同蠕变温度下的未变质ZL205A合金,且0.3%的La变质ZL205A合金的表观应力指数最高,未变质和La变质ZL205A合金的蠕变控制机制为高温位错滑移或者攀移;La变质处理后,ZL205A合金中纳米θ′相的析出数量有所增多,且纳米θ′相的高温稳定性得到改善;蠕变前后,0.3%的La变质ZL205A合金晶界处断续颗粒状Al11La3相的形貌未发生明显变化,在高温蠕变过程中可以起到阻碍晶界运动的作用。
The creep behavior of ZL205A alloy with un-metamorphic and La-containing metamorphism at high temperature of 180, 200 and 220 ℃ was analyzed. The microstructure evolution of the unmetamorphosed and degenerated ZL205A alloy under different temperature and applied stress was explored. The mechanism of high temperature creep of La-modified ZL205A alloy was analyzed. The results show that under the same creep temperature and applied stress, the steady-state creep rate of La-degenerated ZL205A alloy is lower than that of the unmodified ZL205A alloy and the lowest when the La content is 0.3%. The La-treated ZL205A alloy The apparent stress exponent of ZL205A alloy is higher than that of the unmodified ZL205A alloy at the same creep temperature, and the apparent stress index of 0.3% La-modified ZL205A alloy is the highest. The creep control mechanism of the unmodified and La metamorphic ZL205A alloy is high temperature dislocation Slipping or climbing. After La metamorphism, the amount of precipitated nano-phase θ ’in ZL205A alloy increased and the high-temperature stability of nano-θ’ phase improved. Before and after creep, 0.3% La-modified ZL205A alloy grain boundaries The morphology of discontinuous granular Al11La3 phase did not change obviously, which could hinder the grain boundary movement during high temperature creep.