Abstract: The Hydroapatite(HA)-Ti functionally graded biomaterial(FGM) was developed by powder metallurgical process. Young’s modulus and thermal
expansion coefficient of HA-Ti composite materials were investigated. The residual thermal stress and strain in HA-Ti FGM and HA/Ti dual laminate (non-
FGM) cooled to room temperature after sintering was analyzed by the classical lamination theory and thermal-elastic mechanics. The results show the HA-Ti
FGM displays the microstructural characteristics of macroscopic inhomogeneity and microscopic continuity. Young’s modulus of HA-Ti composite materials is
affected by the porosity and reaches its valley point at Ti-HA80. The thermal expansion coefficient increases with the rise of the testing temperature and
HA content. The residual thermal stress and strain strongly depends on the constitutional distribution. In FGM, the maximal residual tensile stress is
only a third of that in non-FGM plate. It is obvious that the HA-Ti FGM has the function of thermal stress relaxation.

Key words: functionally graded material, biomaterial, thermal stress relaxation, hydroxyapatite(HA), Ti