Ti 50Cu 23Ni 20Sn 7 bulk metallic glasses prepared by mechanical alloying and spark-plasma sintering

Abstract

A powder metallurgy technology was developed to prepare Ti 50Cu 23Ni 20Sn 7 bulk metallic glasses (BMGs). Firstly, amorphous powder was prepared by mechanical alloying (MA) method successfully after being milled for 30 h. Phase transformation of the as-milled powder was characterized by X-ray diffraction (XRD). Morphology of the as-milled amorphous powder was observed by scanning electron microscopy (SEM). Onset temperature of glass transformation and onset temperature of crystallization ( T x and T g) of the as-milled amorphous powder were evaluated by differential scanning calorimeter (DSC). Secondly, the as-milled amorphous powder was then consolidated by spark-plasma sintering (SPS) method into a specimen with the shape of cylindrical stick, with a diameter and height of about 20 and 10 mm, respectively. The SPS experiment was conducted under a pressure of 500 MPa at a heating rate of 40 K/min, sintering and holding for 1 min at the temperature of 763 K. It was confirmed that the as-milled powder is of fully amorphous however the consolidated specimen shows to be an amorphous matrix with partial crystallization. Compressing strength, Young's modulus, micro-hardness, friction and density of the consolidated specimen are about 975 MPa, 121 GPa, 13 GPa, 0.12 and 6599 kg/m 3, respectively. Fractograph of the specimen appears to be shear fracture and very few defects can be seen from the picture of SEM.