scholarly journals Structure–Property Relationships in Shape Memory Metallic Glass Composites

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1419 ◽  
Author(s):  
Daniel Şopu ◽  
Xudong Yuan ◽  
Franco Moitzi ◽  
Mihai Stoica ◽  
Jürgen Eckert
Keyword(s):  
Metallic Glass ◽  
Shape Memory ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Pure Copper ◽  
Shear Bands ◽  
High Volume ◽  
Structural Features ◽  
Structure Property ◽  
Glass Composites

Metallic glass composites with shape memory crystals show enhanced plasticity and work-hardening capability. We investigate the influence of various critical structural aspects such as, the density of crystalline precipitates, their distribution and size, and the structural features and intrinsic properties of the phase on the deformation behavior of metallic amorphous Cu 64 Zr 36 composites with B2 CuZr inclusions using molecular dynamics simulations. We find that a low density of small B2 inclusions with spacing smaller than the critical shear band length controls the formation and distribution of plastic zones in the composite and hinders the formation of critical shear bands. When the free path for shearing allows the formation of mature shear bands a high volume fraction of large B2 precipitates is necessary to stabilize the shear flow and avoid runaway instability. Additionally, we also investigate the deformation mechanism of composites with pure copper crystals for comparison, in order to understand the superior mechanical properties of metallic glass composites with shape memory crystals in more detail. The complex and competing mechanisms of deformation occurring in shape memory metallic glass composites allow this class of materials to sustain large tensile deformation, even though only a low-volume fraction of crystalline inclusions is present.

Homogeneous flow of bulk metallic glass composites with a high volume fraction of reinforcement

2007 ◽  
Vol 22 (6) ◽  
pp. 1564-1573 ◽  
Author(s):  
X.L. Fu ◽  
Y. Li ◽  
C.A. Schuh
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Volume Fraction ◽  
High Volume ◽  
Strain Rate Range ◽  
Homogeneous Deformation ◽  
Deformation Analysis ◽  
Glass Composites ◽  
Glass Matrix Composites

We present a systematic study of homogeneous deformation in a La-based bulk metallic glass and two in situ composites based on the same glass. In contrast to prior investigations, which focused on relatively dilute composites, in this work the reinforcement volume percentages were more concentrated at 37% and 52%—near or above the percolation threshold (35–40%). Hot uniaxial compressive testing was conducted over a wide strain rate range from 10−2to 10−5s−1at a temperature near the glass transition. For such concentrated composites, the homogeneous deformation behavior appeared to be dominated by the properties of the reinforcement phase; in the present case the La reinforcements deformed by glide-controlled creep. Post-deformation analysis suggested that bulk metallic glass matrix composites were susceptible to microstructural evolution, which appeared to be enhanced by deformation, in contrast with a stress-free anneal. Consequently, unreinforced bulk metallic glass appeared to be more structurally stable than its composites during deformation near the glass transition.

scholarly journals Role of Glass Composition on Mechanical Properties of Shape Memory Alloy-Metallic Glass Composites

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Supat Chupradit ◽  
Indah Raya ◽  
Dinh Tran Ngoc Huy ◽  
Dmitry Bokov ◽  
Pham Van Tuan ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Md Simulation ◽  
Shear Bands ◽  
Laminated Composite ◽  
Softening Effect ◽  
Glass Composites ◽  
Wide Range ◽  
Tension Loading

In this work, the molecular dynamics (MD) simulation was applied to design a laminated composite structure comprised of the shape memory alloy (SMA) and Cu-Zr metallic glasses (MGs). A wide range of MG compositions was considered to tune the mechanical features and improve the homogenous plastic deformation during the tension loading. The results indicated that the martensitic transformation in the SMA inhibited the sudden shear band propagation in the composite for all the samples. Moreover, it was revealed that the mechanism of plasticity was significantly affected by the change of MG composition. In the Cu-rich MGs, the formation and propagation of thick shear bands occurred at the end of the tension loading; however, the increase in Zr content induced the interaction of multiple shear bands with finer configurations in the system. Nevertheless, the excessive Zr addition in the MG composition facilitated the aggregation of nanopores at the interface of SMA and MGs, which may be due to the softening effect in the Zr-rich MGs. Finally, it is concluded that an optimized MG composition is required for the trade-off between the plasticity and the strength in the SMA-MG composites.

Ti–Cu–Ni shape memory bulk metallic glass composites

2013 ◽  
Vol 61 (1) ◽  
pp. 151-162 ◽  
Author(s):  
P. Gargarella ◽  
S. Pauly ◽  
K.K. Song ◽  
J. Hu ◽  
N.S. Barekar ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Shape Memory ◽  
Bulk Metallic Glass ◽  
Glass Composites ◽  
Bulk Metallic Glass Composites

The Compressive Response of Idealized Cermetlike Materials

2015 ◽  
Vol 82 (4) ◽  
Author(s):  
Eral Bele ◽  
Vikram S. Deshpande
Keyword(s):  
Granular Media ◽  
Volume Fraction ◽  
Solder Matrix ◽  
Shear Bands ◽  
High Volume ◽  
Large Strains ◽  
Compressive Response ◽  
Hard Particles ◽  
Random Arrangement ◽  
Inclusion Volume

Metals reinforced with a high volume fraction of hard particles, e.g., cermets, have properties that are more akin to those of granular media than conventional composites. Here, the mechanical properties and deformation mechanisms of this class of materials are investigated through the fabrication and testing of idealized cermets, comprising steel spheres in a Sn/Pb solder matrix. These materials have a similar contrast in the properties of constituent phases compared to commercial cermets; however, the simpler microstructure allows an easier interpretation of their properties. A combination of X-ray tomography and multiaxial strain measurements revealed that deformation at large strains occurs by the development of shear bands similar to granular media, with the material dilating under hydrostatic pressure within these shear bands. Predictions of finite element models with a random arrangement of inclusions were in excellent agreement with the experimental results of idealized cermets. These calculations showed that at large inclusion volume fractions, composites with a random arrangement of inclusions are significantly stronger compared to their periodic counterparts, due to the development of a network of force chains through the percolated particles.

scholarly journals Brittle-Ductile Transition in Laser 3D Printing of Fe-Based Bulk Metallic Glass Composites

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 78 ◽  
Author(s):  
Fei Xie ◽  
Qingjun Chen ◽  
Jiwen Gao
Keyword(s):  
Plastic Deformation ◽  
3D Printing ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Volume Fraction ◽  
Elastic Recovery ◽  
Plasticity Index ◽  
Glass Composites ◽  
Bulk Metallic Glass Composites ◽  
Brittle Ductile Transition

The effects of the α-Fe phase on mechanical properties and cracking of laser 3D printing Fe-based bulk metallic glass composites were investigated. The elastic recovery and plasticity index were characterized by nanoindentation. As the volume fraction of the α-Fe phase increases from 23.66% to 52.38%, the elastic modulus of printed samples suddenly drops. The samples exhibit a lower deformation resistance, and the plasticity index increases gradually. When the volume fraction of the α-Fe phase is 67.84%, the interaction between the α-Fe phase and matrix phase is smaller during expansion shrinkage. As a result, cracking is easy to initiate, which leads to the highest crack rate of the printed sample. However, as the volume fraction of the α-Fe phase increases to 83.31%, the hard brittle phase was sandwiched between the α-Fe phases similar to the finger structure plays key role in the plastic deformation. The plastic deformation releases large amounts of stress concentrated at the boundary and suppresses crack formation.

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