Thermal stability of (CoCrFeNi)(94)Ti2Al4 alloy containing coherent nanoprecipitates at intermediate temperatures
Thermal stability of (CoCrFeNi)(94)Ti2Al4 alloy containing coherent nanoprecipitates at intermediate temperatures
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含有相干纳米沉淀物的(CoCrFeNi)(94)Ti2Al4合金在中温下的热稳定性
DOI：
10.1016/j.mtla.2020.100775
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Jin K.
中科院分区：
文献类型：
--
作者：
Zheng Y.;Jia N.;Qian F.;Wang J.;Xue Y.;Jin K.
研究了含有共格纳米析出物的(CoCrFeNi)(94)Ti2Al4合金在723-923K的中间温度下的热稳定性。时效12-168h后，(CoCrFeNi)(94)Ti2Al4合金的组织演变呈现出晶内和晶界附近的特征，初生相L1(2)在晶内保持了良好的稳定性，但与1000K以上的情况不同，在该温度范围内的粗化速度并不显著低于传统的镍基合金。在923K时效过程中，高密度的细小尺寸二次L1(2)析出物形成在围绕初生相的一个狭窄的无沉淀区之外，A(3)B型析出物中的A亚晶格被二次析出物中比一次析出物中更高比例的Ni所占据。此外，在晶界附近观察到Heusler相和不连续析出区，晶界与晶内呈线性排列的析出物排。尽管显微组织如此复杂，但在这一中温区，晶界总体上表现出良好的热稳定性。
The thermal stability of (CoCrFeNi)(94)Ti2Al4 alloys containing coherent nanoprecipitates is investigated at intermediate temperatures of 723-923 K. The microstructure evolution is characterized both inside grains and near grain boundaries upon aging for 12-168 h. The primary L1(2) precipitates within grains maintain good stability, but unlike the cases at temperatures above 1000 K, the coarsening rate in this temperature regime is not significantly lower than the conventional Ni-based alloys. High density of fine-scaled secondary L1(2) precipitates are formed outside a narrow precipitate-free zone surrounding the primary precipitates during aging at 923 K, and the A sublattice in such A(3)B-type precipitates are occupied by higher fraction of Ni in the secondary precipitates than in the primary ones. Furthermore, Heusler phases and discontinuous-precipitate area are observed near grain boundaries, between which and grain interior shows a linearly-arranged precipitate row. Despite such complex microstructure, overall good thermal stability is identified at grain boundaries in this intermediate-temperature regime.