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采用定向凝固技术,研究了Al-35La合金的组织形貌特征、力学性能及其形成条件。结果表明,定向凝固Al-35La合金试样中的枝晶沿主干方向成分是不连续的,表现为周期性双相枝晶组织。对其力学性能进行测试发现,各定向凝固试样压缩性能较好,硬度值较高。分析了Al-35La合金周期性双相枝晶的形成条件。讨论了一定强度的对流在枝晶形核与长大过程中起到的促进溶质交换、带走结晶潜热的作用。由此认为,一定强度的对流促进了Al-35La合金液中两相的交替形核和生长,最终在合金中形成周期性双相枝晶组织。
The directional solidification technique was used to study the microstructure, mechanical properties and forming conditions of Al-35La alloy. The results show that the dendrites in the directionally solidified Al-35La alloy specimens are discontinuous along the trunk direction, showing periodic dual-phase dendrites. The mechanical properties of the test found that the directional solidification of the sample compression better, higher hardness values. The formation conditions of periodic dual-phase dendrite in Al-35La alloy were analyzed. The convection of a certain intensity is discussed in the process of dendrite nucleation and growth to promote solute exchange and take away the latent heat of crystallization. Therefore, a certain intensity of convection promotes the alternating nucleation and growth of two phases in the Al-35La alloy liquid and finally forms a periodic dual-phase dendritic structure in the alloy.