Direct Comparisons of the Fatigue Behavior of Bulk-Metallic Glasses and Crystalline Alloys
Recent research works on bulk-metallic glasses (BMGs) have opened a window to create a new generation of structural materials for applications. Although the mechanical behavior of BMGs is being studied widely, the fatigue characteristics are poorly understood. The uniaxial tension-tension high-cycle fatigue (HCF) studies were performed on zirconium (Zr)-based bulk-metallic glasses (BMGs): Zr50Cu40Al10, Zr50Cu30Al10Ni10, Zr50Cu37Al10Pd3, and Zr41.2Cu12.5Ni10Ti13.8Be22.5, in atomic percent. The HCF experiments were conducted using an electrohydraulic machine at a frequency of 10 Hz with a R ratio of 0.1, where R = σmin./σmax., where σmin. and σmax. are the applied minimum and maximum stresses, respectively. The fatigue-endurance limit of Zr50Cu37Al10Pd3 was significantly greater than those of Zr50Cu40Al10, Zr50Cu30Al10Ni10, and Zr41.2Ti13.8Cu12.5Ni10Be22.5. In order to compare the fatigue property with the crystalline alloys, the same HCF experiments were also performed on Ti-6-4, drill tool steel, and Al 7075. The fatigue lifetime of Zr-based BMGs is generally comparable to those of Ti-6-4 and drill-tool-steel crystalline alloys and is greater than that of Al 7075 alloy. The fracture morphology of BMGs indicates that fatigue-crack-propagation region included the distinct rough striations and the fine striations. The possible mechanism for the striation formation was proposed.
Dr. T. S. Srivatsan, FASM, FASME
G.Y. Wang et al., "Direct Comparisons of the Fatigue Behavior of Bulk-Metallic Glasses and Crystalline Alloys", Key Engineering Materials, Vols. 378-379, pp. 329-338, 2008