Electron microscopy of interfaces in a wollastonite — tricalcium phosphate bioeutectic®

The study investigated the morphology and structure of interfaces between a pseudowollastonite (psW) and α‐tricalcium phosphate (α‐TCP) eutectic ceramic material (Bioeutectic®) obtained by slow solidification (0.5 °C h−1) through the eutectic temperature region (1402 ± 3 °C) of the binary system. The eutectic material contained 60 wt% psW and 40 wt% α‐TCP and was composed of spherical colonies formed by alternating radial lamellae of psW and α‐TCP phases. Small quantities of impurities were found to affect the microstructure and ultrastructure of adjacent colonies. The observations showed the presence of dislocation loops and dislocation pairs in the psW phase away from the interfaces with α‐TCP. The α‐TCP phase remained defect‐free. Two types of interface were identified between the triclinic high‐temperature form of wollastonite (psW) and orthorhombic α‐TCP. In single colonies, the phases were aligned with [011¯]psW and [001¯] α‐TCP. High‐resolution electron microscopy revealed differences in morphologies between the two interfaces, and showed that the lattice planes in the interfaces were defect‐free.