Microstructural Changes During Plastic Deformation and Corrosion Properties of Biomedical Co-20Cr-15W-10Ni Alloy Heat-Treated at 873 K
- 158 Downloads
Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass pct) alloy heat-treated at 873 K (600 °C) for 14.4 ks, and analyzed by electron backscatter diffraction and in situ X-ray diffraction techniques. The obtained results revealed that the area fraction of the ε-phase (f ε ) in the as-received alloy was higher than that in the heat-treated alloy in the low-to-middle strain region (≤ 50 pct), whereas the f ε of the heat-treated alloy was higher than that of the as-received alloy at the fracture point. During plastic deformation, the ε-phase was preferentially formed at the twin boundaries of the heat-treated alloy rather than at the grain boundaries. According to the transmission electron microscopy observations, the thin ε-phase layer formed due to the alloy heat treatment acted as the origin of deformation twinning, which decreased the stress concentration at the grain boundaries. The results of anodic polarization testing showed that neither the heat treatment at 873 K (600 °C) nor plastic deformation affected the alloy corrosion properties. To the best of our knowledge, this is the first study proving that the formation of a thin ε-phase layer during the low-temperature heat treatment of the studied alloy represents an effective method for the enhancement of the alloy ductility without sacrificing its strength and corrosion properties.
This study was financially supported by the Japan Society for the Promotion of Science KAKENHI (Grant Number JP 16J04279).
- 2.P. Poncin and J. Proft: Med. Device Mater., Proc. Mater. Process. Med. Devices Conf., 2003, pp. 253–59.Google Scholar
- 3.F.R. Morral: J. Mater., 1966, vol. 1, pp. 384–412.Google Scholar
- 15.N. Yukawa and K. Sato: Mater. Trans. JIM, 1968, vol. 9, pp. 680–686.Google Scholar
- 17.P. Poncin, B. Gruez, P. Missillier, and P. Comte-Gaz: Med. Device Mater. III, Proc. Mater. Process. Med. Devices Conf., 2006, pp. 85–90.Google Scholar
- 18.P. Poncin, C. Millet, and J. Chevy: Med. Device Mater. II, Proc. Mater. Process. Med. Devices Conf., 2nd, 2004, pp. 279–83.Google Scholar
- 19.W. Walke, Z. Paszenda and J. Tyrlik-Held: Journal of Achievements in Materials and Manufacturing Engineering, 2006, vol. 16, pp.74–79.Google Scholar
- 22.D. T. Sawyer, A. J. Sobkowiak and J. L. Roberts, Jr.: Electrochemistry for Chemists, 2nd ed., John Wiley & Sons, New York, NY, 1995, pp 192.Google Scholar