Effect of TiB, TiC and Y2O3 on tensile properties and creep behavior at 650 degrees C of titanium matrix composites

Two kinds of (TiB + TiC + Y2O3)/alpha-Ti composites with different TiB and TiC contents and the corresponding matrix alloy were prepared by induction skull melting. The results showed that the matrix alloy possessed a typical widmanstatten structure while the composites displayed a basket-weave structure characterized by alpha lamellae with different orientations. Obvious TiB/TiC structures were observed with the increase of re-inforcements, which were very stable in the tensile and creep processes at high temperature. The ultimate tensile strength at 650 & DEG;C increased from 589 MPa to 730 MPa and 812 MPa with the increase of re-inforcements. The enhancement in strength of the composites was elucidated on the load transfer strengthening of the reinforcements. The creep properties of the composites at 650 ? have been sig-nificantly improved due to the impediment of reinforcements and silicides to dislocation movement. The strengthening effect increased with the increase of reinforcements and stress. At 650 Y2O3/290 MPa, compared with the matrix alloy, the creep life of composite with highest reinforcements content was increased by 931% and the steady-state creep rate was reduced by 93%. According to the different stress levels, the composites exhibited different creep behaviors. At 230 MPa, the sub-grains were obvious and the number of actuated dislocations is small. At 290 MPa, the dislocation pile-up was serious and the obviously coarsened silicides lost their pinning effect. (C) 2022 Elsevier B.V. All rights reserved.