Critical Crystallization for Embrittlement in Metallic Glasses.
Phys Rev Lett
; 115(26): 265502, 2015 Dec 31.
Article
em En
| MEDLINE
| ID: mdl-26765004
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 â¼6% by volume does not measurably affect fracture toughness. When exceeding â¼6%, 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 â¼7% 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.
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MEDLINE
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En
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2015
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Article