Neutron in situ crystallization studies of Ti-based BMGs

The phase evolution upon heating of Ti40Zr25Cu9Ni8Be18 BMG was investigated by in situ neutron diffraction studies and compared to Differential scanning calorimetry measurements performed at the same heating rate. When the experiment is performed at the constant speed of 2 K/min, the amorphous to crystallization process proceeds by two complicated crystallization reactions: firstly, the precipitation of a cubic Ti(Zr)Be2 phase at 608 K (a = 6.603 Å), this phase then disappears at 810 K, secondly, by the formation at 749 K of two phases which have been determined by neutron diffraction to be a C14 hexagonal Laves phase and a big cube (Zr,Ti)2Ni phase. When the sample is heated at 2 K/min, then hold at Tg + 158 = 713 K (before Tx2 = 749 K) the (Ti,Zr)Be2 phase develops. After 60 min, the big cube phase starts to appear, an important amorphous bump being still present. These in situ diffraction experiments and the different phases formed are presented and discussed.