Effect of Re and Al additions on the microstructure and mechanical properties of Nb-18Ti-12W alloy
Microstructure and mechanical properties at 25–1200 °C of new refractory alloys, Nb-18Ti-12W (NTW), Nb-18Ti-12W-5Re (NTW-R) and Nb-18Ti-12W-5Re-1Al (NTW-RA), all compositions are in atomic percent, are reported. The alloys are developed as an alternative to a denser, more expensive and difficult-to-process refractory alloy WC-3009. After production by arc melting and hot isostatic pressing at 1400 °C, 207 MPa for 3 h, the alloys have a BCC crystal structure with the average grain size of ~150–200 μm and contain low volume fraction of (Ti,N)-rich precipitates near grain boundaries. NTW shows excellent malleability at all studied temperatures. Its yield stress at 25 °C, 1000 °C and 1200 °C is 874 MPa, 353 MPa and 202 MPa, respectively. The NTW-R and NTW-RA alloys are stronger at all the studied temperatures; however, they lack in compression ductility at 25 °C. As a result, extensive deformation twinning and formation of intergranular voids precede the fracture of these two alloys at 25 °C.