Crystallization behavior of melt-spun and injection cast Ti-Zr-Cu-Ni-Be alloys have been studied by using differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Ti40Zr28Cu9Ni7Be16 and Ti34Zr31Cu10Ni8Be17 amorphous alloys crystallized through a two step process during heating: Nanoscaled primary I-phase precipitated from an amorphous matrix first and the remaining amorphous phase crystallized into the cubic β-Ti(Zr) phase for Ti40Zr28Cu9Ni7Be16 alloy and to hexagonal Laves phase for Ti34Zr31Cu10Ni8Be17 alloy. The I-phase is stable at lower temperature and transforms into a Laves phase at high temperature through an endothermic reaction. Reversible transformation between the I-phase and Laves phase takes place during cyclic heating and cooling. In-situ composites consisting of I-phase embedded in an amorphous matrix can be fabricated by either heat treatment of fully amorphous phase or by controlling cooling rate during solidification. At lower cooling rate, I-phase forms as primary crystal in undercooled liquid and remaining liquid solidified into a glass.
Bibliographical noteFunding Information:
This work was supported by Creative Research Initiatives of Korea Ministry of Science and Technology. One of the author (W.T. Kim) thanks for the partial financial support from the Center for Advanced Materials Processing (CAMP) of the 21st Century Frontier R&D Program funded by the Ministry of Science and Technology, “Republic of Korea”.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering