Microstructure and strength of a novel heat-resistant aluminum alloy strengthened by T-Al6Mg11Zn11 phase at elevated temperatures
Microstructure and strength of a novel heat-resistant aluminum alloy strengthened by T-Al6Mg11Zn11 phase at elevated temperatures
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DOI：
10.1016/j.msea.2018.10.034
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
N. Takata;M. Ishihara;Asuka Suzuki;M. Kobashi
中科院分区：
文献类型：
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作者：
N. Takata;M. Ishihara;Asuka Suzuki;M. Kobashi
利用Al - mg - zn三元体系中较大的α相和T相两相区，设计了一种α-Al （fcc）基体由T- al6mg11zn11（立方）金属间相强化的铝基合金。热力学分析评估了Al-5Mg-3.5Zn（%）的组成，α-Al相由高分数（约10%）的T相增强。在α-Al基体中，T相在晶界处优先析出，时效过程中晶界处T相的面积分数增大。当温度高于300 ℃时，T相的颗粒状析出物在α- al基体中分布均匀，呈(1−11)α//(1−21)Tand [011]α//[111]的取向关系。在200 ℃时效后，晶粒内部出现了大量平均尺寸为~20 nm的细小析出物，可能是与T相相关的亚稳相。该合金（在200 °C预时效1 h）在200 °C时显示出约260 MPa的高屈服强度，远远高于传统铝合金在与涡轮增压器压气机叶轮相应的高温下的屈服强度。
We designed an aluminum (Al)-based alloy with the α-Al (fcc) matrix strengthened by the T-Al6Mg11Zn11(cubic) intermetallic phase using a large two-phase region of α and T phases in the Al–Mg–Zn ternary system. Thermodynamic analysis assessed a composition of Al–5Mg–3.5Zn (at%) with the α-Al phase reinforced with high fractions (approximately 10%) of T phase. We observed that the T phase preferentially precipitated at grain boundaries in the α-Al matrix, increasing the area fraction of the T phase at grain boundaries during aging. The granular precipitates of the T phase were dispersed rather homogenously in the α-Al matrix with a particular orientation relationship of (1−11)α// (1−21)Tand [011]α// [111]Tat temperatures above 300 °C. After aging at 200 °C, numerous fine precipitates with a mean size of ~20 nm in the grain interior were observed, which were likely the metastable phase associated with the T phase. The present alloy (pre-aged at 200 °C for 1 h) exhibited a high yield strength of approximately 260 MPa at 200 °C, much higher than those of the conventional Al alloys at elevated temperatures corresponding to service temperatures for compressor impellers in turbochargers.