Ab initio molecular dynamics model for density, elastic properties and short range order of Co–Fe–Ta–B metallic glass thin films

• Published in: Journal of physics. Condensed matter Vol. 23; no. 47; pp. 475401 - 7
• Main Authors: Hostert, C, Music, D, Bednarcik, J, Keckes, J, Kapaklis, V, Hjörvarsson, B, Schneider, J M
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 30.11.2011; Institute of Physics
• Subjects: Amorphous materials; Cobalt; Condensed matter: structure, mechanical and thermal properties; Density; Disordered solids; Distribution functions; Exact sciences and technology; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik; Glasses; Mathematical models; Mechanical and acoustical properties; Metallic glasses; Molecular dynamics; Physical properties of thin films, nonelectronic; Physics; Physics with spec. in Atomic, Molecular and Condensed Matter Physics; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin films; Quaternary alloys; Elastic modulus; Tantalum alloys; Molecular dynamics method; Nanoindentation; Iron alloys; X-ray reflection; Glass structure; XRD; Electronic density of states; Boron alloys; Young modulus; Metallic glasses; Short-range order; Chemical composition; Ab initio calculations; Pair distribution function; Cobalt alloys; Transition element alloys
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/0953-8984/23/47/475401

Density, elastic modulus and the pair distribution function of Co-Fe-Ta-B metallic glasses were obtained by ab initio molecular dynamics simulations and measured for sputtered thin films using x-ray reflectivity, nanoindentation and x-ray diffraction using high energy photons. The computationally obtained density of 8.19 g cm(-3) for Co(43)Fe(20)Ta(5.5)B(31.5) and 8.42 g cm(-3) for Co(45.5)Fe(24)Ta(6)B(24.5), as well as the Young's moduli of 273 and 251 GPa, respectively, are consistent with our experiments and literature data. These data, together with the good agreement between the theoretical and the experimental pair distribution functions, indicate that the model established here is useful to describe the density, elasticity and short range order of Co-Fe-Ta-B metallic glass thin films. Irrespective of the investigated variation in chemical composition, (Co, Fe)-B cluster formation and Co-Fe interactions are identified by density-of-states analysis. Strong bonds within the structural units and between the metallic species may give rise to the comparatively large stiffness.