Effect of strain hardening and volume fraction of crystalline phase on strength and ductility of bulk metallic glass composites

Shear bands of as-cast and semi-solid Ti48Zr27Cu6Nb5Be14 bulk metallic glass matrix composites

“…In the 1970s, Turnbull D revealed that the formation of the shear bands meant the occurrence of plastic deformation of amorphous alloys, and the deformation was concentrated in the local areas around the shear bands [10] . By studying the relationship between shear band characteristics and the plasticity of BMGMCs [11][12][13] , it was found that the plasticity was improved effectively as the quantity of shear band increased. It was also found that a single shear band would easily lead to brittle fracture with very low plasticity, while multiple shear bands could enhance the plasticity [14] .…”

Numerical investigation of tensile response of notched bulk metallic glass composite specimens

“…A finite strain, non-local plasticity theory proposed from rigorous treatment of continuum thermodynamics by Thamburaja [29] is used to represent the constitutive response of the matrix in the FE simulations to be carried out below because it satisfactorily predicts the mechanical response of BMGs [26,29,30], nanoglasses [31], nanoglass-MG laminate composites [32] and BMGCs [15,16]. In this model, the free volume ξ is a key state variable which evolves due to diffusion, plastic shearing, hydrostatic stress, and structural relaxation, as given by:…”

“…However, the governing parameters associated with these phenomena were not clearly identified. To get more insights, Shete et al [15] performed continuum finite element (FE) simulations on BMGC tension samples with various V f and hardening exponents, N, of dendrites. They found that SBs penetrate the dendrites with low N (∼0.1) while they circumvent those with high N (∼0.3).…”

Investigation on the mechanically-induced nanocrystallization in metallic glasses

“…To circumvent the problem of room-temperature brittleness, several post treatment methods have been introduced including surface mechanical treatment [9], defect printing [10], ion irradiation [11], notching [12], and ultrasonic excitation [13]. Other attempts aimed to hinder localized shear band formation by ex-situ mixing or in-situ generating a micro/nano-scale crystallites embedded in amorphous matrixes to produce a composite structure, consisting of a crystalline phase embedded in an amorphous matrix [14][15][16][17]. Numerous experimental data showed an improvement of the material's properties due to the effect of the introduced second phase [18 -21].…”