1994 年 43 巻 490 号 p. 785-791
The sin2ψ method of X-ray stress measurement was successfully applied to hipped hydroxy-apatite. The X-ray elastic constants of (072+352) diffraction by Mn-Kα radiation was determined experimentally. It is close to the value calculated from the elastic constants of single crystals on the basis of Kröner's model. The residual stress measured on the lapped and ground surfaces was tension, because micro-fracturing was predominant in the grinding process of hydroxyapatite. The bending fracture was started from the cluster of pores. The critical value of the stress intensity factor calculated from the bending strength and the size of the fracture origin was nearly equal to the fracture toughness determined by bending specimens with a single-edge V-shaped sharp notch.