Fe3Al基合金焊接技术的研究进展

纳米金属丝具有优越的敏感性、场发射效能、超强的记忆功能等特性,于是对它的研究便备受青睐.通过定向凝固NiAl-Re复相共晶,再结合选择性溶解或腐蚀的方法来制备Re纳米丝,即DSW技术.利用Bridgman定向凝固设备对NiAl-1.5at％Re共晶合金进行定向凝固,在约300 K/cm的温度梯度条件下,通过改变凝固抽拉速率获得不同的NiAl-Re准共晶组织,研究分析了NiAl-Re共晶的显微结构、凝固速率与纤维相间距、纤维大小的相关性.发现随着凝固速率的增大,纤维相间距和纤维尺寸都逐渐减小,并且两者与凝固速率的平方满足良好的线性关系.使用HCl∶H2O2的蒸馏水稀释溶液对NiA1基体进行选择性腐蚀,这一过程会形成对共晶体的各向异性腐蚀,在被腐蚀的表面上会出现直径为450～500 nm、长度不一的铼纤维丝.腐蚀得到的Re纳米丝可望应用于纳米电极阵列中.

Research Progress in Welding Technology of Fe3Al Based Alloys

The investigations of the metallic nanowires have received great attention due to their excellent properties of predominate sensibility, field emission and great memory functions. Rhenium nanowires were fabricated through directional solidification and selective etching of a NiAl-Re eutectic alloy, which is called the DSW (Directional Solidification Nanowires) technique. A NiAl-1.5at%Re eutectic alloy was directionally solidified in a Bridgman-type directional solidification furnace under a temperature gradient of 300 K/cm. Different size and morphologies of NiAl-Re eutectics were obtained by changing the growth rate. The microstructures of the NiAl-Re eutectic alloys and the relationship between growth rate and the spacing of the fibers as well as the size were analyzed. It is found that the fiber spacing and the fiber sizes decrease gradually with the increasing of the growth rate, and both of them have well linear relation with the square of the growth rate. The selective dissolution of the NiAl matrix was achieved with a mixture of HCl:H2O2. This procedure produces an anisotropic etching of the eutectic. The corroded surface is dominated by rhenium fibers (diameter of 450~500 nm) with different length. The fibers obtained might subsequently be applied for the preparation of nanoelectrode arrays