Effects of Changes in Chemistry on Flex Bending Fatigue Behavior of Al-Based Amorphous Alloy Ribbons
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The effects of changes in composition on the flow behavior and flex bending fatigue behavior of a series of Al-Gd-Ni-X (X = Fe or Co) amorphous alloy ribbons have been determined at 1 Hz at room temperature. It has been shown that the addition of Fe, Co, and Fe/Co combination into these materials increases the strength, T g, and T x1 in addition to the activation energy for crystallization. The lowest strength (i.e., 880 MPa) base alloy Al87Gd6Ni7 exhibited the best low-cycle fatigue (LCF) and worst high-cycle fatigue (HCF) behavior, whereas the higher strength alloys (~1100 MPa) Al85Gd6Ni7Fe2 and Al85Gd6Ni7Fe1Co1 exhibited worse LCF and better HCF behavior. The ratio of the stress amplitude at the fatigue limit at 1 × 106 cycles to uniaxial failure strength ranged from 0.25 to 0.37 (240 to 397 MPa), much higher than conventional aluminum alloys. These results are also compared with those obtained on other amorphous alloy ribbons.
KeywordsFatigue Fatigue Limit Stress Amplitude Bulk Metallic Glass Fatigue Crack Growth Rate
The authors thank the DARPA-SAM 2 program for support through Pratt & Whitney Corporation. The supply of materials from Pratt & Whitney and Ames laboratory is gratefully acknowledged. Useful discussions with A. L. Greer and G. J. Shiflet are also appreciated. Technical support was provided by the MMC group of Case Western Reserve University.
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