Effect of grain size on spall fracture of CrCoNi medium-entropy alloy under Taylor-wave loading

Y Deng and J Cheng and C Wan and J Xu and Y Chen and JY Huang and HY Zhao and Y Cai, JOURNAL OF ALLOYS AND COMPOUNDS, 1002, 175452 (2024).

DOI: 10.1016/j.jallcom.2024.175452

The effect of grain size on spall properties of medium-entropy alloy CrCoNi under Taylor-wave loading is investigated. Three different grain sizes, 300 mu m, 20 mu m, and 3 mu m, are explored. The free surface velocity histories are measured to obtain such quantities as dynamic yield strength and spall strength. With decreasing grain size, there is a slight decrease in spall strength, but a significant increase in damage rate. The shockrecovered samples are characterized with scanning electron microscopy and electron backscatter diffraction. In coarse- grained samples, voids tend to nucleate within grain interiors, while in fine-grained samples, voids nucleate preferentially at grain boundaries (GBs). Molecular dynamics simulations show that the nucleation of intergranular or intragranular voids is dominated by GB-slip and slip- slip intersections, respectively. The higher GB density results in more extensive GB-slip intersections, consistent with the experimental results.

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