Materials Chemistry and Physics, Vol.163, 512-517, 2015
Microstructure and mechanical properties of an ultrafine Ti-Si-Nb alloy
Nb-modified ultrafine Ti-Si eutectic alloy was made by cold crucible levitation melting, tested in compression at room temperature, and characterized by electron microscopy. Compression tests of (Ti86.5Si3.5)(97)Nb-3 specimens measured an ultimate compressive strength of 1180 MPa and a compressive plastic strain of 12%, both of which are higher than in eutectic Ti86.5Si13.5 alloy. Electron microscopy showed that the Ti Si Nb alloy had a bimodal microstructure with micrometer-scale primary alpha-Ti dendrites distributed in an ultrafine eutectic (alpha-Ti Ti5Si3) matrix. The enhanced ductility is attributed to the morphology of the phase constituents and to the larger lattice mismatches between alpha-Ti and Ti5Si3 phases caused by the NU addition. The crystallographic orientation relationship of Ti5Si3 with alpha-Ti is (1 (1) over bar 00)[(1) over bar(1) over bar 26] Ti5Si3(1) over bar1 (01T1) alpha-Ti. (C) 2015 Elsevier B.V. All rights reserved.