Metallic glasses are frequently used as structural materials. Therefore, it
is important to develop methods to predict their mechanical response as a
function of the microstructure prior to loading. We develop a coarse-grained
spring network model, which describes the mechanical response of metallic
glasses using an equivalent series network of springs, which can break and
re-form to mimic atomic rearrangements during deformation. To validate the
model, we perform simulations of quasistatic, uniaxial tension of Lennard-Jones
and embedded atom method (EAM) potentials for Cu50​Zr50​ metallic
glasses. We consider samples prepared using a wide range of cooling rates and
with different amounts of crystalline order. We show that both the
Lennard-Jones and EAM models possess qualitatively similar stress σ
versus strain γ curves. By specifying five parameters in the spring
network model (ultimate strength, strain at ultimate strength, slopes of
σ(γ) at γ=0 and at large strain, and strain at fracture
where σ=0), we can accurately describe the form of the stress-strain
curves during uniaxial tension for the computational studies of
Cu50​Zr50​, as well as recent experimental studies of several Zr-based
metallic glasses. For the computational studies of Cu50​Zr50​, we find
that the yield strain distribution is shifted to larger strains for slowly
cooled glasses compared to rapidly cooled glasses. In addition, the average
number of new springs and their rate of formation decreases with decreasing
cooling rate. These effects offset each other at large strains, causing the
stress-strain curve to become independent of the sample preparation protocol in
this regime. In future studies, we will extract the parameters that define the
spring network model directly from atomic rearrangements that occur during
uniaxial deformation.Comment: 16 pages, 13 figure