Structure and Properties of Semifinished Sheet Products Made of an Intermetallic Refractory Alloy Based on Ti2AlNb

摘要

We study the influence of two-stage thermal treatment on the formation of the phase composition, structure, and mechanical properties of semifinished sheet products made of VTI-4 refractory alloy based on the Ti2AlNb intermetallic compound. It is shown that, changing the temperature of heating in the first stage of treatment and the temperature of subsequent aging, it is possible to affect the strength and plasticity characteristics of the material in broad ranges. It is demonstrated that, in order to obtain a structure guaranteeing a relative elongation of 8-12%, the temperature of the first stage of treatment must remain in the (beta + alpha(2) + O) three-phase region and the procedure of cooling down to room temperature or to the temperature of the second stage of treatment (800-850A degrees C) should be realized together with the furnace. To get high levels of short- and long-term strength at 650A degrees C with preservation of moderate values of plasticity (3-5%), it is necessary to perform cooling after isothermal treatment in the three-phase region in air. The subsequent procedure of aging should be carried out within the temperature range 800-850A degrees C for 7 h.