Abstract
This paper aims to investigate the thermal behavior and crystallization kinetics of TiZrHfNiCu high entropy bulk metallic glass (HE-BMG) alloy using the standard procedure of Differential Scanning Calorimetric (DSC) annealing technique. The alloy was produced using an arc melting machine with a critical diameter of 1.5 mm. The crystallization kinetics and phase transformation mechanism of TiZrHfNiCu HE-BMG was investigated under the isochronal condition at a single heating run based on the Johnson-Mehl- Avrami (JMA) theory. In isochronal heating, the apparent activation energy for glass transition and crystallization events was analyzed by Kissinger and Ozawa methods. The average activation energy value for crystallization of TiZrHfNiCu amorphous alloys in isochronal modes was 226.41 kJ/mol for the first crystallization and 297.72 kJ/mol for second crystallization stages. The crystallization mechanism of the first step was dominated by two- and three-dimensional growth with increasing nucleation rate, while the crystallization mechanism in the second stage was dominated by two-dimensional crystallization growth with a constant nucleation rate. The diffusion mechanism result proved the theory of sluggish atomic diffusion of HEA at elevated temperature.
Highlights
This paper aims to investigate the thermal behavior and crystallization kinetics of TiZrHfNiCu high entropy bulk metallic glass (HE-Bulk Metallic Glasses (BMGs)) alloy using the standard procedure of Differential Scanning Calorimetric (DSC) annealing technique
High Entropy Alloys (HEAs) have been defined as a near equiatomic ratio of multi-component alloys that form simple phases of body-centered cubic (BCC), face-centered cubic (FCC) or hexagonal closed packed (HCP) that resulted from high entropy effect [1] while BMGs is a non-crystalline metallic alloy with a disordered atomic-scale structure that produced by rapid cooling method [3]
Kinetics of crystallization in TiZrHfNiCu HE-BMG was investigated by DSC method in non-isothermal condition
Summary
High Entropy Alloys (HEAs) and Bulk Metallic Glasses (BMGs) are two types of novel materials that exhibit unique physical and mechanical properties [1] [2]. HEAs have been defined as a near equiatomic ratio of multi-component alloys that form simple phases of body-centered cubic (BCC), face-centered cubic (FCC) or hexagonal closed packed (HCP) that resulted from high entropy effect [1] while BMGs is a non-crystalline metallic alloy with a disordered atomic-scale structure that produced by rapid cooling method [3]. High entropy effect in HE-BMGs results in low viscosity of the alloy melt it is expected to produce low glass-forming ability (GFA) alloy. Numerous researches on the investigation of kinetics have been presented with different approaches in clarifying the crystallization process, including mechanism, activation energy and correlation between kinetics and structural in amorphous alloys. The first report on crystallization kinetics of HE-BMG was published by Gong, Yao, and Ding in 2015 by choosing Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 as composition using both non-isothermal and isothermal modes [5]
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