title: Critical Crystallization for Embrittlement in Metallic Glasses.
abstract: We studied the effect of crystallization on the embrittlement of bulk metallic glasses. Specifically, we measured fracture toughness for Zr(44)Ti(11)Cu(10)Ni(10)Be(25) and Pd(43)Cu(27)Ni(10)P(20) after annealing at various times to introduce controlled volume fraction of crystallization. We found that crystallization of up to ∼6% by volume does not measurably affect fracture toughness. When exceeding ∼6%, a dramatic drop in fracture toughness occurs; an additional 1% of crystallization reduces fracture toughness by 50%. Such a dramatic transition can be explained by the interaction among the crystals' stress fields in the amorphous matrix that becomes effective at ∼7% crystallinity. Our findings of a critical crystallization for embrittlement of metallic glasses help in designing tough metallic glasses and their composites, as well as defining processing protocols for the unique thermoplastic forming of metallic glasses to avoid embrittlement.
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University, New Haven, Connecticut 06511, USA.
authors.forename: Jittisa
authors.initials: J
authors.lastname: Ketkaew
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University, New Haven, Connecticut 06511, USA.|Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072, China.
authors.forename: Ze
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University, New Haven, Connecticut 06511, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University, New Haven, Connecticut 06511, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Schroers