SGER: Magnetically-Triggered Joining Using Nanocrystalline Fe-Al Powders

在不降低材料性能的前提下，有效、廉价地连接材料，特别是异种材料，具有很大的实用价值。本奖项的研究目的是评估一种新的连接方法。该方法涉及使用交变磁场（AMF）在两相纳米晶粉末中产生磁滞损耗，其中一相是铁磁性的，另一相是铝。当粉末受到适当强度和频率的AMF时，铁磁相加热，引发相之间的放热反应。这种由磁触发的反应产生的热量可以用来熔化粉末，直接形成一个接头，加热焊料或钎焊的连接层，或者熔化要连接的材料的表面。由反应产生的金属铝化物将凝固成一种新的非铁磁性晶体结构，这种结构随后不能被AMF加热。研究工作将是生产粉末，表征它们的微观结构和磁性，并检查在应用的AMF下连接不同的材料。该方法是通用的，原则上可以应用于许多材料并用于许多应用。

Joining materials, particularly dissimilar materials, effectively and inexpensively while not degrading their properties is of great practical value. The research objective of this award is to evaluate a proposed new method for joining. The method involves using an alternating magnetic field (AMF) to generate hysteresis losses in two-phase nanocrystalline powders in which one of the phases is ferromagnetic and the other is aluminum. When the powders are subjected to an AMF of appropriate strength and frequency, the ferromagnetic phase heats up, triggering an exothermic reaction between the phases. The heat output from this magnetically-triggered reaction can be used to either melt the powders to form a joint directly, heat a joining layer of solder or braze, or melt the surfaces of the materials to be joined. The metal aluminide resultingfrom the reaction will solidify into a new non-ferromagnetic crystal structure, which cannot be subsequently heated by an AMF.The research effort will be to produce powders, characterize them both microstructurally and magnetically, and examine joining different materials under an applied AMF. The method is generic and could, in principle, be applied to many materials and used for many applications.