Influence of processing on the microstructure of Cu–8Cr–4Nb
- 124 Downloads
The particle-strengthened Cu–8 at.%Cr–4 at.%Nb alloy is processed by consolidation of atomized powders followed by extrusion to obtain bars and rolling to produce sheets. Comparison of copper matrix grain and second-phase particle structures in both extruded and rolled Cu–8Cr–4Nb was performed. Extruded material displayed locally banded arrangements of Cr2Nb particles, while the distribution of particles was more uniform in rolled material. Mean Cr2Nb particle sizes were found to be essentially the same for both processing methods. Non-spherical particles in the extruded alloy showed some preferred orientation, whereas the rolled material displayed a more uniform particle orientation distribution. Extruded material exhibited a dual grain size distribution with smaller grains in banded regions. The mean grain size of 1.36 μm in extruded material was larger than the 0.65 μm grain size of rolled material. A  texture was evident in extruded material, whereas the rolled material was only slightly textured along the  and  directions. The processing differences for the rolled and extruded forms give rise to different microstructures and hence higher creep strength for the extruded material in the temperature range of 773–923 K.
KeywordsCreep Strength Extrusion Direction Interparticle Spacing Copper Matrix Rolled Material
This work was funded as part of NASA Grant NCC3-859. The authors wish to thank Drs. David Ellis and Michael Nathal for their continuing support and advice regarding this project. The authors also wish to express their appreciation to Dr. George Kaschner of the Los Alamos National Laboratory for the kind use of the SEM/EBSD equipment, which resulted in the OIM images used in this study.
- 3.(a) Chakrabati DJ, Laughlin DE (1982) Bull Alloy Phase Diagrams 2:507; (b) Chakrabati DJ, Laughlin DE (1984) Bull Alloy Phase Diagrams 5:59, 99Google Scholar
- 6.Ellis DL, Michal GM (1999, Sep) NASA Contractor Report 185144Google Scholar
- 7.Ellis DL, Misra AK, Dreshfield RL (1996) In: Thompson AW, Moody NR (eds) Proceedings of the fifth international conference on the effect of hydrogen on the behavior of materials. TMS, Warrendale, pp 1049–1056Google Scholar
- 10.Decker MW (2003) Constant stress creep properties of extruded Cu-8Cr-4Nb (GRCop-84). M.S. Thesis, University of California, DavisGoogle Scholar
- 12.Shewmon PG (1983) Transformations in metals. J. Williams Book Company, Oklahoma, pp 69–125Google Scholar
- 13.Ellis DL, Garg A (to be published) Annealing behavior of GRCop-84. NASA Technical Memorandum. NASA Glenn Research Center, Cleveland, OHGoogle Scholar