NiAl-W共晶定向凝固组织控制与W介纳米丝形貌

The Microstructure Control of NiAl-W Eutectic Directional Solidification and the Morphology of W Meso-nanowires

摘要:

在300 K/cm 的温度梯度条件下，实施不同抽拉速率下的NiAl-1.5at%W共晶合金定向凝固，分析研究抽拉速率对W纤维相相间距、纤维相尺寸的影响规律，并使用盐酸双氧水溶液对NiAl基体进行选择性溶解，制备出当量直径小于500nm的钨纤维丝束。研究结果表明：随着抽拉速率的增大，W纤维相截面形状圆度增加， W纤维相相间距和W纤维相截面当量直径均减小，两者的比值在6.12到7.54之间，经选择性溶解获得W纤维具有多样的三维形貌，呈现出薄带状、珍珠串状和搭接状，发现其形貌与抽拉速率有关。

关键词:介纳米金属丝;定向凝固;共晶合金;选择性溶解

Abstract:

Under a temperature gradient of 300 K/cm, NiAl-1.5at%W eutectic samples were directionally solidified at the different drawing rates to analyze the effect of the drawing rates on the spacing and the size of W fiber phases. Moreover. the NiAl matrix was selectively etched by using a solution of HCl:H2O2 to prepare the tunsten fiber filaments with the equivalent diameter less than 500 nm. The research results show that the roundness of W fiber phase cross-section increases, the spacing and the equivalent diameter of W fiber phase both decreases, the ratio between them is in the range of 6.12 to 7.54, as increasing the drawing rate; and that the tungsten fibers obtained by selective dissolution have the diversiform three-dimensional morphologies, such as the thin strip, pearl string and lapping state, which have been found that those shapes have a relationship with the drawing rate.

Key words:metallic meso-nanowires; directional solidification; eutectic alloy; selective dissolution