稀土元素对原位合成TiB_2/Al复合材料组织和性能的影响

采用原位合成法研究稀土元素Ce,Sc,Er对TiB_2/Al复合材料TiB_2颗粒和基体组织的影响,并对复合材料的拉伸性能进行分析。结果表明,稀土元素的添加显著改善了复合材料的组织和性能。添加0.3%(质量分数)Sc和Er的复合材料的TiB_2颗粒分布相对均匀,稀土元素Er对基体合金的组织细化效果最显著,其次是Sc。添加稀土Sc和Er元素的复合材料拉伸强度较好,分别提高了32%和31%,添加稀土Er元素的复合材料伸长率最佳,提高了85%,因此,其拉伸性能也最佳。添加稀土元素Sc和Er后,复合材料的断裂形式为微孔聚集型的韧性断裂。稀土元素对复合材料的作用机理表现在两方面:一是稀土元素的添加改善了复合材料的润湿性,并抑制了TiB_2颗粒的团聚;另一方面,稀土元素的添加使得基体合金组织细化,从而提高了复合材料的拉伸强度。

Effect of Rare Earth Element on Microstructure and Properties of in situ Synthesized TiB2/Al Composites

The effect of rare earth element Ce,Sc and Er on TiB2 particles and matrix alloy microstructure of TiB2/Al composites was studied with in situ synthesis method.It shows that the addition of rare earth element improves the microstructure and properties of TiB2/Al composites notably.The particles of TiB2 are relatively homogenously distributed as adding 0.3 ％ (mass fraction) rare earth element Sc and Er,moreover,it is Er that refines the microstructure of matrix alloy most significantly,then is Sc.Similarly,it is demonstrated that the addition of Sc and Er results in better tensile strength,which is enhanced by 32％ and 31％,respectively;the addition of Er also leads to the best ductility by 85％ with optimal tensile property.Meanwhile,fracture morphology analysis reveals that the fracture of the composites is microporous gathered ductile fracture when adding Sc and Er.Finally,it is verified that the mechanism of rare earth element on composites lies in two aspects:one is that the addition of rare earth element improves the wettability of the composites and suppresses the agglomeration of TiB2 particles;the other is that the addition of rare earth element refines the microstructure of matrix alloy and then improves the tensile strength of the composites.