Metallurgical Abstracts on Light Metals and Alloys vol.55

Effects of Cerium on Crystal Orientation Dependence of Fatigue Fracture Behavior of Magnesium Single Crystals

Guojun Lu*, Kensuke Miyazaki*, Hiromoto Kitahara* and Shinji Ando*
*Kumamoto University

[Published in Materials Transactions, Vol. 63, No. 1 (2022) pp. 27–32]

https://doi.org/10.2320/matertrans.MT-L2021013
E-mail: shinji[at]msre.kumamoto-u.ac.jp
Key Words: S-N plot, fracture surface, basal slip, twin, pyramidal slip

Fatigue tests of single crystalline Mg–0.026 at% Ce were carried out to investigate the effects of cerium on crystal orientation dependence of fatigue lives. A plane bending fatigue test method for thin sheet specimen was employed. Three crystal orientations were investigated: B specimen with [1100](0001), D specimen with [1120](1100) and E specimen with [0001](1120). Fatigue lives increased by the cerium addition in D and E crystal orientations, but decreased in B crystal orientation. The cerium additions decreased critical resolved shear stress (CRSS) for second order pyramidal slip, resulting in ridge and stripe (RS) patterns which were observed on fracture surfaces in B specimen. A fatigue crack propagation mechanism was proposed to account for the RS patterns.

(Left) Fatigue S-N plots of Mg-0.026 at% Ce single crystals with different orientations.
(Right) Fatigue crack propagation mechanism of (a) pure magnesium single crystal and (b) Mg-Ce single crystals.