1. 1) E.B. KULA and S.L. LOPATA: Trans. AIME, 215 (1959), p.980
2. 2) A. JONES and WALKER: Metal Sci,, 8 (1974), p.397
3. 4) U. LOTTER, L.MEYER, R.D. KONRR, and D.HAMBORN: Arch. Eisenhüttenw., 47 (1976), p.289
4. 5) H. INAGAKI: Trans. ISIJ, 17 (1977), p.166
5. 6) F. BORIK and R.H. RICHMAN: Trans. AIME, 239 (1967), p.675