EFFECTS OF THORIA PARTICLES ON THE HIGH-TEMPERATURE TENSILE PROPERTIES OF A W-26WT-PERCENT-RE ALLOY

The tensile properties of powder-metallurgy-processed W-26wt.%Re and W-26wt.%Re-1wt.%ThO2 were examined over the temperature range 1600-2600 K in a strain rate range 10(-3)-10(-2)s-1. It was found that the addition of ThO2 particles significantly reduced grain boundary migration and hence stabilized the microstructure of W-26Re at elevated temperatures. ThO2 particle strengthening in W-26Re was effective up to about 2200 K. The strengthening mechanisms were attributed to microstructure stabilization, misfit dilatation, and inhomogeneous deformation in the vicinity of ThO2 particles. The addition of ThO2 increased both temperature sensitivity and strain rate sensitivity of W-26Re at high temperatures. Post-test specimens were characterized by scanning electron microscopy and transmission electron microscopy. Both W-26Re-1ThO2 and W-26Re exhibited an intergranular fracture mode when fractured at high temperatures.