Joining Al 6061 to ZE41A Mg Alloy by Friction Stir Welding Using a Cold Spray Transition Joint

Abstract

The joining of highly dissimilar metals such as aluminum and magnesium has proven to be a difficult challenge using most of the technologies available today. This paper presents a novel method to join dissimilar materials using a combination of two advanced metals processing technologies, friction stir welding (FSW) and cold spray. By utilizing both technologies the strengths of each can be employed, while at the same time mitigating otherwise disqualifying aspects if used alone. In this study, cast ZE41A-T5 magnesium was joined to wrought 6061 aluminum. The joint was accomplished by first cold spraying a 6061 transition zone onto the magnesium alloy, followed by FSW of a 6061 plate to the cold sprayed 6061 zone. Utilizing this method, the formation of detrimentally thick intermetallic layer between the aluminum and magnesium was avoided, providing a resultant joint which matched the strength of the magnesium cast alloy. Detailed materials characterization by electron and optical microscopy, along with mechanical test results is presented. Comparisons to conventional joining techniques and potential applications of this technique is discussed.