Published online by Cambridge University Press: 10 February 2011
To investigate the deformation behavior of the C15 HfV2+Nb Laves phase, compression tests were conducted on the C15/bcc two-phase alloys at very low temperatures down to 4.2 K. Transmission electron microscopy revealed that substantial mechanical twinning takes place in the C15 Laves phase at room temperature and 77 K. A deep minimum in the flow stress, with a drop of nearly 500 MPa, appears at around 77 K for the C15/bcc two-phase alloy. Since no such anomaly is seen in the bcc phase, we believe that the cause of this can be attributed to mechanical twinning in the C15 Laves phase. A high density of ultra-fine twin bands is the characteristic feature of twinning in the C15 matrix. We also investigated the phase relations between the C15 HfV2 Nb and bcc (V, Nb) solid solution in the Hf-V-Nb ternary system in an attempt to understand why we were unsuccessful in our attempts to grow single crystals of the Laves phase.