Micro indentation study on Cu60Zr20Ti20 metallic glass

Abstract

Abstract In the present investigation, deformation behavior of melt spun glassy ribbon of Cu 60 Zr 20 Ti 20 has been studied using microhardness test. Further, the glassy ribbon was annealed at supercooled liquid region (Δ T x ), offset of first crystallization ( T x 1 ) and offset of second crystallization temperature ( T x 2 ). X-ray diffraction and transmission electron microscopy has been used to understand the crystallization behavior of the glass and to correlate its microstructural evolution with the mechanical properties. The glassy alloy initially undergoes phase separation during annealing which transforms into a totally crystalline structure after annealing at T x 2 temperature. It has been observed that at any particular load, the hardness of the alloy increases with the progress of phase separation and partial crystallization. After complete crystallization the hardness drops off. This leaves behind the scope of microstructural engineering of metallic glasses and composites for best enhancement of properties. Further the role of phase separation on the indentation behavior of this glassy alloy has been explored. The role of relaxation and crystallization on hardness and deformation behavior of glassy ribbon alloy is examined by observing the indentations under scanning electron microscopy. Results indicate that the composite structure formed during annealing at T x 1 has superior hardness in comparison to other microstructures.