A new thermodynamic parameter to predict glass forming ability in iron based multi-component systems containing zirconium

Abstract

A new thermodynamic parameter P_HSS (P_HSS = ΔH^C(ΔS_σ/k_B)(ΔS_C/R)) is proposed, to describe and predict the Glass Forming Ability (GFA) of Fe based alloys. Here ΔH^C is the chemical enthalpy of mixing, ΔS_σ is the mismatch entropy and ΔS_C is the configurational entropy. The P_HSS parameter incorporates enthalpy of mixing, size mismatch and the number of elements in the systems which influence GFA significantly. It was observed from Rapid Solidification Processing (RSP) and Mechanical Alloying (MA) studies that, all alloys with P_HSS in between −0.55 kJ/mol to −6.00 kJ/mol would form glass in the Fe–Zr–B system. MA and RSP experiments on multi-component Fe–Cr–Ni–Zr–B alloys indicated that P_HSS is a better parameter to predict GFA of the system than P_HS, a parameter used in earlier studies. It was also observed that Bulk Metallic Glass (BMG) forming alloys can be observed in between a P_HSS range of −3.00 kJ/mol to −6.00 kJ/mol, with the maximum thickness of the BMG increasing with decreasing P_HSS within the above range.