U.S.-Korea Cooperative Research on the Application of Non-Destructive Techniques to Investigate Cavitation in Superplasticity

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This award provides funds to permit Dr. Terence G. Langdon, Department of Materials Science, University of Southern California (USC), to pursue with Dr. Ho Chul Kim, Professor of Physics, Korea Advanced Institute of Science and Technology (KAIST), for 24 months, a program of cooperative research on the application of non- destructive techniques to the investigation of cavitation in superplasticity. Their research formerly was supported under NSF Grant No. INT-8803709. These scientists and members of their research groups will continue their collaboration through the use of destructive superplastic testing, at USC, with non- destructive ultrasonic velocity and photoacoustic spectroscopy (PAS) at KAIST. They will (1) use metallography, at USC to verify PAS results obtained at KAIST, (2) extent their procedures to include lower elongations, and (3) expand their investigations to include materials other than metals. Superplasticity refers to the ability of some metals to exhibit exceptionally high, neck-free elongations, often in excess of 1,000%, when pulled in tension at elevated temperatures. This phenomenon is of considerable commercial interest because of the many potential applications in sheet-metal forming. A major problem in superplasticity is the nucleation and growth of internal cavities. These cavities may lead to a significant degradation of the post-forming properties of the material. It is important, therefore, to estimate the volume of cavities, non-destructively, and to verify these estimates using metallographic techniques. The collaborators are highly respected scientists in the field of this research. Their past collaboration has resulted in significant contributions to the literature of this field. The U.S. scientist will benefit from access to facilities for non-destructive testing, available at KAIST, but not at USC. This project is relevant to the objectives of the U.S.-Korea Cooperative Science Program which seeks to increase the level of cooperation between U.S. and Korean scientists and engineers through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit. Korean participation in the project is supported by the Korea Science and Engineering Foundation (KOSEF).