Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 02, 2019 - November 04, 2019
Fatigue tests on Zr55Cu30Ni5Al10 zirconium (Zr)-based bulk metallic glass were conducted under four-point bending either in air or in distilled water environment. Bulk Metallic Glasses (BMGs) are expected to be applied for many structural applications because of remarkable properties like high strength and high corrosion resistance. However, the knowledge of the fatigue strength and on the fatigue characteristics on newly developed BMGs is still insufficient. The purpose of the present study is to grasp the fatigue characteristics and the conditions of corrosion fatigue crack initiation for Zr55Cu30Ni5Al10 BMG. Experimental results highlight an earlier fatigue crack initiation in distilled water than in air due to stress concentration at the corrosion pits. The aspect ratio, α, of the corrosion pits where the fatigue crack initiated is approximately 1.4 regardless the stress level. To investigate the conditions of corrosion fatigue crack initiation, artificial small defect simulating corrosion pits was introduced on specimen surface. The aspect ratio, α, of fractured surface is approximately 1.6. In addition, the fatigue crack initiated from the artificial defects all has α = 1.0 or more. It suggests that it is necessary to consider the shape of the pit to define the fatigue crack initiation condition.
