The cellular interlamellar and growth-front interphase boundaries in Cu-3 Wt pct Ti

Examination of the cellular colony interlamellar and growth-front interphase boundaries in Cu-3 wt pct Ti reveals an influence of crystallography at both of these interface types. Analysis of the interlamellar boundaries demonstrates that different arrangements of interphase misfit-compensating defects exist and combinations of misfit dislocations (MDs), structural ledges (SLs), or direction steps (DSs) were observed to dominate strain reduction between lamellae, even within the same colony. Detailed analysis also demonstrated that the actual interlamellar orientation relationship (OR) is (111) _α ‖ (010) _β with -101] _α ‖ 501] _β , which is 0.28 deg in misorientation from the reported OR. The effect of crystallography was also apparent at the cellular growth front, as evidenced by the misfit-compensating structure observed with transmission electron microscopy (TEM) at the grain-boundary segments and the sharp faceting of all β precipitate-growth interfaces. This article is based on a presentation in the symposium “Interfacial Dislocations: Symposium in Honor of J.H. van der Merwe on the 50th Anniversary of His Discovery,” as part of the 2000 TMS Fall Meeting, October 11–12, 2000, in St. Louis, Missouri, sponsored under the auspices of ASM International, Materials Science Critical Technology, Sector, Structures.