Fracture of Isotropic and Textured Ba Hexaferrite

The effects of texture and temperature on the fracture toughness of an oriented Ba hexaferrite were studied. An isotropic ferrite was also measured. Anisotropy of K le at room temperature in the oriented ferrite was a factor of 3, with the transgranular fracture having a K lc of 2.83 MN‐m −3/2 . Toughness decreased with increasing temperature, exhibiting two regions of behavior: a low‐temperature brittle elastic fracture region of — (dK lc /dT) of 10‐ −4 MN · m −3/2 . °C −1 and a distinct high‐temperature region of 10‐ −2 MN · m −3/2 . °C −1 which exhibited 100% grain‐boundary fracture.