On Prediction of Amorphous Phase Forming Compositions in the Iron-Rich Fe-Zr-B Ternary System and Their Synthesis
- PDF / 558,532 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 77 Downloads / 152 Views
ODUCTION
MECHANICAL alloying (MA) and mechanical milling are promising routes to synthesize amorphous powders in bulk quantity.[1–3] Amorphous phase formation by the MA route depends on several process parameters and the elemental constitution of initial powders.[4,5] The amorphous phase forming ability (AFA) of an alloy can be predicted from elemental constitution using glass forming ability (GFA) models, though GFA specifically refers to the ease with which a liquid alloy transforms to an amorphous solid (glass) on cooling. There were several attempts to identify GFA of metallic alloys, ever since the first metallic glass was discovered by Clement et al.[6] in the Au-Si system by rapid solidification processing (RSP). Development of bulk metallic glasses (BMGs) has led to the realization that intrinsic factors such as constituting atomic species, their relative sizes, their packing, and the heat of mixing play a more important role in deciding GFA than external factors such as cooling rate. This realization was culminated in three empirical rules proposed by Inoue.[7]
B. RAMAKRISHNA RAO, Scientist, is with the Naval Materials Research Laboratory, Ambernath, Thane 421506, India. A.K. SHAH, Scientist, formerly with the Naval Materials Research Laboratory, is now with the Panipat Institute of Engineering and Technology, Panipat, Haryana, PIN 132102, India. M. SRINIVAS, Scientist, is with the Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058, India. J. BHATT, Associate Professor, is with the Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur 440010, India. A.S. GANDHI, Assistant Professor, and B.S. MURTY, Professor, are with the Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India. Contact e-mail: [email protected] Manuscript submitted August 13, 2010. Article published online July 15, 2011 METALLURGICAL AND MATERIALS TRANSACTIONS A
Several authors attempted to identify different GFA parameters in an alloy system using thermal analysis results.[8–12] However, all these parameters were not predictive in nature due to the necessity of making alloy first and evaluation of their thermal parameters. Gallego et al.[13] proposed a predictive model to identify glass forming compositions in binary alloys and ternary alloys based on free energy considerations, which was demonstrated by Murty et al.[5] for the first time in the Ti-NiCu system. CALPHAD and other approaches based on thermodynamics and kinetics of amorphous phase formation in binary alloys were reviewed recently by Palumbo and Battezzati.[14] In a more recent approach, thermodynamical and topological models were combined to yield a parameter PH-S, which is a product of enthalpy of chemical mixing and mismatch entropy.[15] It was proposed that glass forming compositions with a favorable PH-S can be identified by ternary intersection points on superimposed isometric contours of mixing enthalpy and mismatch entropy. It has been demo
Data Loading...
