Design of Fe-Based Bulk Metallic Glasses with Improved Wear Resistance.

Abstract

The application of bulk metallic glasses (BMGs) as advanced wear-resistant materials has remained limited despite optimistic expectations. In this work, we develop a series of novel Fe-based BMGs with improved wear resistance by altering the Cr and Mo contents in an Fe-Cr-Mo-C-B-Y glass-forming system. Experimental results demonstrate that increasing Cr and Mo contents enhance the thermal stability and hardness ( Hv) of the resulting BMGs without reducing their fracture toughness ( Kc). The enhanced hardness is mainly attributed to the increased fraction of the stiff (Cr,Mo)-C covalent bonds in the resultant BMGs, as revealed by X-ray photoelectron spectrograph measurement. Worn surface/subsurface observations and stress field modeling reveal the activity of two kinds of wear mechanisms, i.e., hardness-controlled abrasion wear and toughness-controlled fatigue wear. We further clarify the enhanced wear performance of the Fe-based BMGs according to an effective indicator Kc3/4 Hv1/2 that correlates positively with the wear resistance of the samples. The optimal Fe-based BMG sample possessed versatile properties, including a strong glass-forming ability (i.e., a critical diameter of 8 mm), a high hardness of 1335 Hv, and a very low specific wear rate of ∼1.3 × 10-6 mm3 N-1 m-1, which represents one of the most outstanding Fe-based BMGs reported thus far.