Abstract
Microstructures produced in the Co-Cr-Mo-C alloy H.S.21 were observed by transmission electron microscopy in cast specimens following solutionizing at 1230°C and aging at 650°C and in low-carbon wrought specimens following solutionizing and aging at 650°C and 750°C. In all cases, aging was found to promote the formation of fcc stacking faults and to cause an initial martensitic transformation from the fcc phase to a heavily faulted hep structure. Precipitate formation was observed in hcp areas of the cast material after 20 h at 650°C and in hcp areas of wrought material after 20 h at 750°C. Prolonged aging at 750°C produced a transformation in the hcp structure of wrought specimens, with a relatively fault-free structure replacing the heavily faulted martensitic form. Interruption of fcc slip by both fcc stacking faults and bands of hcp phase was found to be the principal strengthening mechanism activated by aging. Precipitate formation in the hcp plays an increasingly significant role as aging time is increased. This microstructural information is used to explain the observed tensile properties of these alloys after the heat treatments mentioned.
Similar content being viewed by others
References
F. R. Morral:J. Mater., 1966, vol. 1, p. 384.
J. T. Scales:J. Bone Joint Surg., 1972, vol. 53B, p. 344.
J. R. Cahoon and H. W. Paxton:J. Biomed. Mat. Res., 1968, vol. 2, p. 1
J. O. Galante, W. Rostoker, and V. M. Doyle:J. Bone Joint Surg., 1975, vol. 57A, p. 230.
J. R. Coke, J. B. Vander Sande, and J. Wulff: to be published inCobalt.
R. Hollander and J. Wulff:Metals Eng. Quart., 1974, vol. 14, p. 37.
F. J. Clauss and J. W. Weeton: Technical Note 3108, National Advisory Committee for Aeronautics, 1954.
G. E. Wasielewski and N. R. Lindblad: Proc. of the Second International Conference on Superalloy Processing, A.I.M.E. Section D-l, 1972.
M. Basaran, T. Z. Kattamis, R. Mehrabian, and M. C. Flemings:Met. Trans., 1973, vol. 4, p. 2429.
J. W. Weeton and R. A. Signorelli: Technical Note 3109, National Advisory Committee for Aeronautics, 1954.
E. E. Fletcher: Summary Report to the Office of Naval Research, Battelle Memorial Institute, March 31, 1952 (Navy Dept. Contract No. N5ori-111, Task Order 1, Project NR031-003).
R. Gevers, A. Art, and S. Amelinckx:Phys. Status Solidi, 1963, vol. 3, p. 1563.
T. M. Devine: Ph.D. Thesis, M.I.T., 1974.
P. A. Beaven: Ph.D. Thesis, University of London, 1973.
K. H. G. Ashbee:Acta Met., 1967, vol. 15, p. 1129.
D. J. H. Cockayne, I. L. F. Ray, and M. J. Whelan:Phil. Mag., 1969, vol. 20, p. 1265.
V. Ramaswamy, P. R. Swann, and D. R. F. West: Proc. of the Fifth International Materials Symposium, University of California at Berkeley, 1971, p. 637.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Vander Sande, J.B., Coke, J.R. & Wulff, J. A transmission electron microscopy study of the mechanisms of strengthening in heat-treated Co-Cr-Mo-C alloys. Metall Trans A 7, 389–397 (1976). https://doi.org/10.1007/BF02642835
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02642835