【摘要】 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。更多还原

【Abstract】 The dendrite structure characteristics,mechanical properties and forming conditions of Al-35La alloy prepared by directional solidification were investigated.The results show that the dendrite structure in Al-35La alloy obtained by directional solidification exhibits discontinuous and periodic two-phase morphology along the main body.The mechanic properties testing shows that the samples obtained exhibit higher compression strength and hardness.Formation mechanism of the periodic two-phase dendrite structure in Al-35La alloy was described.Convection with a certain intensity will take off crystallization latent heat in the liquid by promoting solute exchanging during nucleation and growth of dendrite.Therefore,it is considered that the convection with a certain intensity will promote the alternately nucleation and growth of two phase in the liquid of Al-35La alloy,resulting in the formation of periodic two-phase dendrite structure in the alloy.更多还原