【摘要】 研究了Al-35%La合金定向凝固组织的形貌特征、形成条件及其力学性能。结果表明:在定向凝固Al-35%La合金试样中,枝晶是成分沿其主干方向呈周期变化的双相组织。各定向凝固试样的力学性能测试发现:压缩性能较好,硬度值较高。分析了Al-35%La合金周期性双相枝晶的形成条件,说明一定强度的对流在枝晶形核与长大中起到促进溶质交换,带走结晶潜热的作用。由此认为,一定强度的对流促进了Al-35%La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 structure morphology features,formation conditions and mechanical properties of the directionally solidified Al-35% La alloy were investigated.The results showed that,in the directionally solidified Al-35% La alloy sample,the dendrite structure was a biphase structure with composition periodically changing along its main trunk direction.The mechanical properties test of every directionally solidified samples revealed that their anti-compression properties were quite good,and hardness values were relatively high.The formation condition of the periodic biphase dendrite of the Al-35%La alloy was analyzed and it was explained that the convection with certain intensity had the effect to promote solutes exchange and take off the crystallization latent heat.Thereby it was considered that the convection with certain intensity promoted the alternative nucleation and growth of two phases of the Al-35%La alloy melt that led finally to the formation of the periodic biphase dendrite structure in the alloy.更多还原