1. A. Gilbert, J. L. Ratliff, and W. R. Wark'e, Trans. AS M 58 (1965) 142.
2. H. Kellerer and G. Piatti, J. Materials. Sci. 3 (1968) 222.
3. G. Beghi, P. Guyot, and G. Piatti, M�m. Sci. Rev. M�t. 61 (1964) 191.
4. A. Giarda, and M. Paganelli, ibid 62 (1965) 921.
5. B. A. Wilcox and A. M. Clauer, Trans. Met. Soc. AIME 233 (1965) 253.