Bulk metallic glasses (BMGs) exhibit high yield strength but little tensile ductility. For this class of materials, damage tolerance is a key mechanical design parameter needed for their engineering use. Recently we have discovered a correlation between the local structural characteristics in the glass and the propensity for shear transformations. Based on the dependence of glass structure on alloy composition, zirconium (Zr)-rich Zr-titanium (Ti)-copper (Cu)-aluminum (Al) compositions are predicted to be more prone to spread-out plastic deformation and hence profuse shear banding. This structural perspective has guided us to locate a Zr61Ti2Cu25Al12 (ZT1) BMG that exhibits a record-breaking fracture toughness, on par with the palladium (Pd)-based BMG recently developed at Caltech. At the same time, the new BMG consists of common metals and has robust glass-forming ability. Interestingly, the ZT1 BMG derives its high toughness from its high propensity for crack deflection and local loading-mode change (from mode I to substantially mode II) at the crack tip due to extensive shear band interactions. A crack-resistance curve (R-curve) has been obtained following American Society for Testing and Materials (ASTM) standards, employing both "single-specimen" and "multiple-specimen" techniques as well as fatigue precracked specimens. The combination of high strength and fracture toughness places ZT1 atop all engineering metallic alloys in the strength-toughness Ashby diagram, pushing the envelop accessible to a structural material in terms of its damage tolerance.
部门归属
[xu, jian] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. [ma, evan] johns hopkins univ, dept mat sci & engn, baltimore, md 21218 usa.
; xu, j (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.
; jianxu@imr.ac.cn
; ema@jhu.edu
J. Xu,E. Ma. Damage-tolerant Zr-Cu-Al-based bulk metallic glasses with record-breaking fracture toughness[J]. Journal of Materials Research,2014,29(14):1489-1499.
APA
J. Xu,&E. Ma.(2014).Damage-tolerant Zr-Cu-Al-based bulk metallic glasses with record-breaking fracture toughness.Journal of Materials Research,29(14),1489-1499.
MLA
J. Xu,et al."Damage-tolerant Zr-Cu-Al-based bulk metallic glasses with record-breaking fracture toughness".Journal of Materials Research 29.14(2014):1489-1499.
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