添加碳纳米管对选区激光熔化AlSi10Mg合金缺陷的影响

The Influence of Carbon Nanotubes on Defects in AlSi10Mg alloy fabricated by Selective Laser Melting

摘要:

利用选区激光熔化成形技术制备了纯AlSi10Mg合金及碳纳米管(Carbon nanotubes, CNTs)-AlSi10Mg复合材料。当添加CNTs含量为0.05wt.%时具有一定增强效果,但随着CNTs添加量增大,复合材料性能却因为缺陷的增加而明显下降。本文利用纳米CT技术对纯合金及CNTs(0.5wt.%)-AlSi10Mg复合材料进行缺陷的三维重构。结果表明,添加0.5wt.%的CNTs后,成形缺陷体积所占比例由12%增加至46%；气孔型缺陷数量明显增加,并且等效直径相对较大。CNTs在粉体中的团聚及对气体的吸附作用是两种类型缺陷增加的根本原因。

关键词:选区激光熔化;AlSi10Mg;碳纳米管;缺陷;纳米CT

Abstract:

Pure AlSi10Mg alloy and Carbon Nanotubes (CNTs)-AlSi10Mg composite with different CNTs addition were fabricated by selective laser melting (SLM). The CNTs-AlSi10Mg composite was strengthened when the CNTs content was lower than 0.05 wt.%. With the increasing CNTs content, however, the strength was decreased significantly because of the poor density. In order to understand the influence of CNTs on the defects in SLMed AlSi10Mg alloy, nano-CT technology was used to get the 3D information of the defects. The results indicated that the volume fraction of large defects(with diameter larger than 50 μm) in the total volume of defects was increased from 12% to 46% in CNTs(0.5wt.%)-AlSi10Mg composite. The number of gas pores in CNTs(0.5wt.%)-AlSi10Mg composite were significantly increased. The diameter of gas pores in CNTs(0.5wt.%)-AlSi10Mg composite were larger than that in pure AlSi10Mg alloy. The agglomeration of CNTs in the powder and gas adsorption are the fundamental reasons for the increase of the two types of defects.

Key words:Selective laser melting; AlSi10Mg; Carbon nanotubes; defect; nano-CT