Brown University School of Engineering

Joint Materials/Solid Mechanics Seminar Series “Atomistic investigation of enhanced tensile ductility of metallic glass and composite”

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Friday, November 16, 2012 4:00pm - 5:00pm

Joint Materials/Solid Mechanics Seminar Series “Atomistic investigation of enhanced tensile ductility of metallic glass and composite” Shaoxing Qu Department of Engineering Mechanics Zhejiang University, China Abstract: Metallic glass matrix composites may have unique mechanical properties and potential for practical applications. Deformation mechanisms governing the structural evolution process of these mixed structures remain poorly understood. We elucidate the effect of the crystalline second phase on the tension behavior of metallic glass matrix composites by using large-scale atomistic simulations. We identify that the interaction between the crystalline second phase and the local shear bands is dominated by the cooperative activation of lattice dislocations on the glass-crystal interfaces and discrete shearing events in the neighboring glass matrix. Heterogeneity can also be introduced into metallic glasses in the form of pre-existing shear bands. The basic idea is to promote and spread plastic deformation in the specimen and thus delay or suppress shear localization. It is found that at a critical density of pre-existing shear band (regardless of its distribution or orientation), the plastic deformation mode of MG will change from inhomogeneous shear localization to homogeneous STZ nucleation. Atomic-scale investigation shows that it is the fluctuation of local shearing that controls this transition. Friday, November 16, 2012 4:00-5:00 pm B&H Room 141