• PDF / 12,595,966 Bytes
• 5 Pages / 612 x 792 pts (letter) Page_size
• 51 Downloads / 252 Views

DOWNLOAD

REPORT

---

This work was conducted as part of the in-house research of the Metals Processing Group of the Air Force Research Laboratory’s Materials and Manufacturing Directorate. The support and encouragement of the laboratory management and the Air Force Office of Scientific Research (Dr. C.S. Hartley, program manager) are gratefully acknowledged. REFERENCES 1. J.W. Martin, R.D. Doherty, and B. Cantor: Stability of Microstructure in Metallic Systems, Cambridge University Press, Cambridge, United Kingdom, 1997, chapter 5. 2. T.H. Courtney and J.C. Malzahn Kampe: Acta Metall., 1989, vol. 37, pp. 1747-58. 3. H.E. Cline: Acta Metall., 1971, vol. 19, pp. 481-90. 4. J.D. Livingston and J.W. Cahn: Acta Metall., 1974, vol. 22, pp. 495-503. 5. Y.G. Nakagawa and G.C. Weatherly: Acta Metall., 1972, vol. 20, pp. 345-50. 6. R.V. Ramanujan, P.J. Maziasz, and C.T. Liu: Acta Mater., 1996, vol. 44, pp. 2611-42. 7. R.A. Fournelle: Acta Metall., 1979, vol. 27, pp. 1147-55. 8. S.L. Semiatin, V. Seetharaman, and A.K. Ghosh: Phil. Trans. R. Soc. A, 1999, vol. 357, pp. 1487-1512. 9. N. Stefansson, S.L. Semiatin, and D. Eylon: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 3527-34. 10. N. Stefansson and S.L. Semiatin: Metall. Mater. Trans. A, 2003, vol. 34A, pp. 691-98. 11. S.L. Semiatin, B.C. Kirby, and G.A. Salishchev: Metall. Mater. Trans. A, 2004, vol. 35A, pp. 2809-19. 12. I. Weiss, F.H. Froes, D. Eylon, and G.E. Welsch: Metall. Trans. A, 1986, vol. 17A, pp. 1935-47. 13. R.D. Doherty and K.E. Rajab: Acta Mater., 1989, vol. 37, pp. 2723-32.

Hardness of Pulsed Electric Current Sintered and Hot Isostatically Pressed Mo(Si,Al)2

spectroscopy (EDS), X-ray diffraction, and a hardness test. Mo(Si,Al)2 was generated by pretreatment using a furnace, and the application of the PECS and HIP treatments further densified the sintered body, resulting in an increase in the hardness.

With recent progress in the technologies for the development of airplanes and spacecraft, the development of hightemperature-resistant materials, which can be used in the temperature range above 1300 K, which is the heat-resistant temperature of super alloys currently used, is desired. As metallic materials for use at super-high temperatures of 1800 K or higher and in an oxidizing atmosphere, silicon compounds and aluminum compounds with high melting points are considered promising. The high-temperature resistance to and oxidization of these metallic materials can be improved by the formation of a protective oxidized film on their surfaces, such as silica (SiO2) or alumina (Al2O3). To date, as a material with superior antioxidization characteristics under high temperatures of 2000 K or higher in air, an intermetallic compound of molybdenum-siliconaluminum, i.e., Mo(Si,Al)2, has been reported by Kisly et al.[1,2] and Maruyama et al.[3,4,5] Figure 1 shows a phase diagram of the Mo-Si-Al system at 1323 K.[5] According to Figure 1, it is expected that Mo(Si,Al)2 can be generated by Mo being soaked into Al-Si liquid saturated with Si. Mo(Si,Al)2 offers the advantage of being a promisi