EVALUATION OF STRUCTURAL CHARACTERISTICS OF TINI AL2O3/TI6AL4V COMPOSITE BIOMATERIAL/

The paper is devoted to the study of structural characteristics of two types of functional biomaterial composed of plasma coated shape memor y TiNi wires which are partly cast under vacuum into Ti6Al4V alloy. Th e alpha-Al2O3 plasma coating, approx. 130 divided by 180 I-lm thick, r eacts with TiNi wire as well as with Ti6Al4V alloy in case of lower co oling rate. Under these conditions, the formed interphases are of Ti-4 (NixAly)(2)(O,N)(z)-type on the side of TiNi alloy and of Ti3Al-type o n the side of Ti6Al4V alloy. For higher cooling rate, these interphase s are not found. Further, the optimum rolling conditions of studied co mposite material TiNi/Al2O3/ /Ti6Al4V are determined. The applied tech nique represents a reasonable compromise between the physical and meta llurgical properties of coexisting constituents. The rolling temperatu re of 900 degrees C, and the reduction in one pass of 5% were recommen ded as optimum. The total deformation of the composite attained after the multipasses rolling is of 30%. The shear strength of TiNi plasma c oated wires and Ti6Al4V alloy is higher than 100 MPa. In case of elimi nation of the transition phases formation (at higher cooling rate) at the interface of coexisting constituents, the shear strength of 60 MPa is found. The failure occurs dominantly in Al2O3 coating for a lower cooling rate and on TiNi/AI(2)O(3) interface in specimens cooled at a higher rate.