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Local melting to design strong and plastically deformable bulk metallic glass composites

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ABSTRACT

Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties. Through adjusting local melting process parameters (i.e. input powers, local melting positions, and distances between the electrode and amorphous plate), the size, volume fraction, and distribution of B2 crystals were well tailored and the corresponding formation mechanism was clearly clarified. The resultant BMG composites exhibit large compressive plasticity and high strength together with obvious work-hardening ability. This compelling approach could be of great significance for the steady development of metastable CuZr-based alloys with excellent mechanical properties.

No MeSH data available.


Lateral morphologies of (a) the heat-affected zone, (b) the glassy matrix, (c) the mixed zone consisting of the heat-affected zone and the molten zone for the locally melting samples after deformation.
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f5: Lateral morphologies of (a) the heat-affected zone, (b) the glassy matrix, (c) the mixed zone consisting of the heat-affected zone and the molten zone for the locally melting samples after deformation.

Mentions: where fα, fβ, and fαβ are the volume fractions of the glassy matrix (α), B2 CuZr crystals (β) larger than 250 μm, and the mixed (α + β) constitute consisting the remaining B2 CuZr crystals and the amorphous phase in a small scale, respectively1017. Furthermore, the , , and are the fracture strains of the α, β, and (α + β) constitutes, respectively. K is a dimensionless constant which accounts for the constraint effect of the α and/or β on the α + β. It is seen that the fracture strain of CuZr-based BMG composites, which also can be used to evaluate the plastic strain since the elastic strain of BMG composites is almost constant (i.e. about 2%)81017, strongly depends on the proportion of the (α + β) constitute and the K constant if the total crystalline volume fraction fβ is fixed. In our case, the zone B mainly consists of the B2 CuZr crystals and the amorphous phase in a small scale (Figs 3 and 5a), whichshould belong to the (α + β) constitute. Compared with previous results81017, the volume fraction of the (α + β) constitute is quite larger in the present BMG composites. As a result, these interdispersed microstructures could lead to significantly improved ductility for the present BMGs composites.


Local melting to design strong and plastically deformable bulk metallic glass composites
Lateral morphologies of (a) the heat-affected zone, (b) the glassy matrix, (c) the mixed zone consisting of the heat-affected zone and the molten zone for the locally melting samples after deformation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5304197&req=5

f5: Lateral morphologies of (a) the heat-affected zone, (b) the glassy matrix, (c) the mixed zone consisting of the heat-affected zone and the molten zone for the locally melting samples after deformation.
Mentions: where fα, fβ, and fαβ are the volume fractions of the glassy matrix (α), B2 CuZr crystals (β) larger than 250 μm, and the mixed (α + β) constitute consisting the remaining B2 CuZr crystals and the amorphous phase in a small scale, respectively1017. Furthermore, the , , and are the fracture strains of the α, β, and (α + β) constitutes, respectively. K is a dimensionless constant which accounts for the constraint effect of the α and/or β on the α + β. It is seen that the fracture strain of CuZr-based BMG composites, which also can be used to evaluate the plastic strain since the elastic strain of BMG composites is almost constant (i.e. about 2%)81017, strongly depends on the proportion of the (α + β) constitute and the K constant if the total crystalline volume fraction fβ is fixed. In our case, the zone B mainly consists of the B2 CuZr crystals and the amorphous phase in a small scale (Figs 3 and 5a), whichshould belong to the (α + β) constitute. Compared with previous results81017, the volume fraction of the (α + β) constitute is quite larger in the present BMG composites. As a result, these interdispersed microstructures could lead to significantly improved ductility for the present BMGs composites.

View Article: PubMed Central - PubMed

ABSTRACT

Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties. Through adjusting local melting process parameters (i.e. input powers, local melting positions, and distances between the electrode and amorphous plate), the size, volume fraction, and distribution of B2 crystals were well tailored and the corresponding formation mechanism was clearly clarified. The resultant BMG composites exhibit large compressive plasticity and high strength together with obvious work-hardening ability. This compelling approach could be of great significance for the steady development of metastable CuZr-based alloys with excellent mechanical properties.

No MeSH data available.