Abstract
The microstructure, phase composition, and mechanical properties of NbTiZr, TaTiZr, Re0.3NbTiZr, and Re0.3TaTiZr are reported. The alloys were produced by vacuum arc melting and hot isostatically pressed (HIP’d) at 1400 °C for 3 h under 276 MPa hydrostatic pressure of high-purity argon prior to testing. NbTiZr had a single-phase BCC crystal structure, while TaTiZr had a Ti- and Zr-rich BCC matrix phase and Ta-rich nanometer-sized BCC precipitates, at volume fractions of 0.49 and 0.51, respectively. Re0.3NbTiZr consisted of a BCC matrix phase and Re-rich precipitates with a FCC crystal structure and the volume fraction of 0.14. The microstructure of Re0.3TaTiZr consisted of a Zr-rich BCC matrix phase and coarse, Re and Ta rich, BCC particles, which volume fraction was 0.47. NbTiZr and TaTiZr had a room temperature (RT) yield stress of 920 MPa and 1670 MPa, respectively. While, 10 at.% Re additions increased the RT yield stress to 1220 MPa in Re0.3NbTiZr and 1715 MPa in Re0.3TaTiZr. Re also considerably improved the RT ductility of TaTiZr, from about 2.5% to 10% of true strain. The positive strengthening effect from the Re additions was retained at high (800–1200 °C) temperatures.
Highlights
The brittleto-ductile transition temperature, TBDT, depends strongly on the alloy composition and microstructure, and it is desirable for structural refractory alloys that the TBDT is below room temperature
The results indicate that in indicate that in the temperature range of 800 °C to 1200
The room temperature (RT) yield stress was 920 MPa, and it decreased from 465 MPa to 61 MPa with increasing temperature from 800 ◦ C to 1200 ◦ C
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Many refractory alloys, including refractory complex concentrated alloys (RCCAs), have a BCC crystal structure and, as many BCC metals, exhibit a brittle-to-ductile transition (BDT) [1,2]. The transition occurs because of a strong temperature dependence of plastic (shear) stress and relatively weak temperature dependence of fracture (cleavage) stress. At low temperatures the shear stress can exceed the cleavage stress, and the BCC material becomes brittle. The shear stress decreases rapidly with increasing temperature, and when it becomes less than the cleavage stress, the material becomes ductile. The brittleto-ductile transition temperature, TBDT , depends strongly on the alloy composition and microstructure, and it is desirable for structural refractory alloys that the TBDT is below room temperature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
