Materials which can be changed in shape and size when exposed to a magnetic field are called magnetostrictive materials. The magnetostrictive material was developed for use in the many actuator industries. A single crystal of magnetostrictive material is used to maximize its magnetostrictive response. It can be produced by the crystal growth method. However, a single crystal from this method is limited in size and shape. The growth direction of a single crystal, sometimes, is different from its magnetostrictive axis. Capacitor discharge welding (CDW) is a high power density welding process at 10���-10��� Kelvin/second. The fusion zone of CDW is very small and the heat affected zone of CDW is rarely detectable. The amount of material affected by heat in the welding process is very small. The objective of this study is to use capacitor discharge welding (CDW) to join single crystal copper and determine the effect of CDW on the microstructure of the single crystal copper. To minimize the cost of using single crystal copper, low oxygen copper C101 (polycrystalline) is used as a replacement. By maximizing the weld strength, Response Surface Methodology (RSM) is used to find the optimum condition of single crystal copper. The single crystal copper was cut at different orientations and welded together with the one that had same orientation to compare the results. The metallography was used to study voids, fusion zone and dislocations of the single crystal copper after welding. After analyzing the effect of the CDW process on the single crystal, the effect of crystal orientation upon void formation was found statistically inconclusive. Small fusion zone as 0.09154 mm was found. No heat affected zone of single crystal was detected. Also, no microstructural damage was found along the fusion zone. Dislocation density before and after CDW were not different because there was no statistically significant difference between the etch pit density in the fusion zone and that outside the fusion zone. In summary, regardless of voids, CDW may be a useful method for welding single crystal metals. / Graduation date: 1999