Exploring plastic bulk metallic glasses
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Exploring plastic bulk metallic glasses
0961120078 蔡敏 09机设（2）班
Abstract: The lack of global plasticity at room temperature is the main barrier to the application
of metallic glasses and to the understanding of their deformation. The improvement of this
plasticity has been a hot topic in metallic glasses research. In this paper we introduce three
feasible methods to enhance the plasticity. Based on the correlation between elastic moduli
(Poisson′s ratio) and plasticity we have designed a series of metallic glasses with large plasticity.
Keywords: metallic glass, plasticity, Poisson′s ratio, shear band
1. foreword
The ideal structure material is high strength and large plastic of a combination of high
strength can carry great weight, good plastic can guarantee the safety of the materials used and not
catastrophic damage. But in a material with hard to high strength and large plastic, the two
properties of a total along with the improvement of the performance of the other properties of the
metal alloy reduced. Glass is melt in solidification process will not occur in the form of
crystallization of amorphous materials. Because of its amorphous structure, with special physical
properties, such as high strength (close to the theoretical value), good elasticity performance
(elastic limit about 2%), good corrosion resistance, resistance to radiation ability and
wear-resisting performance, is a kind of extensive application prospect new functional materials
and potential of structural materials [1-3]. However, metal glass at normal temperature of plastic
deformation is through the local area, high shear bring realize. The width of the shear zone only 10
to 50 nm, but bear the whole materials macro plastic deformation. Because shear zone of the
material volume fraction is small, so in the macro, most metal glass presents brittle, almost no
macro plastic deformation [4-6]. Therefore, metal glass to become a widely used of structural
materials, must overcome its brittleness, realize the macro plastic.
Shear zone and the formation of the expansion are metal glass in process of elastic
deformation release can and carrying plastic deformation of the main mechanism [4-6]. So if you
want to improve the metal plastic, from shear zone of shear band. Since carrying a metal glass in
all the deformation of the stress process, so long as improve the density of shear band, let the
production of large Numbers of and prevent metal glass along a single shear zone fracturing, it is
possible to overcome the brittle metal glass. From the start, clues in recent years we have certain
put forward the team to explore the plastic metal glass of modulus criterion, develop high pressure
processing, parcel restrictions, shot peening etc effectively improve the method of plastic metal
glass; And according to poisson's ratio and metal glass plastic relationship (modulus criterion, the
design gives a) large plastic deformation of the ability of Zr fund glass system. These results to
overcome metal glass provide the feasible brittle method and design idea of glass material
deformation mechanism research provides model material.
2. Improve the method of metal glass and plastic
In order to improve the metal glass of plastic, the researchers first thoughts is the method of
composite materials. In the amorphous substrate into the second phase-plastic particles amorphous
state [7, 8]. This form of composite materials, in the process of shear deformation, once the local
area in amorphous substrate occurs, the second phase particles will put plastic shear zone isolated,
to prevent the spread of the shear zone and then realizing big plastic deformation. On the other
hand, the second phase particles as a defect, also can be used as a shear zone of inducing the point,
produce more of the shear zone. So, sample participate in plastic deformation of the increased
volume fraction, no longer confined to a few shear belt in the big can cause plastic deformation.
But this method is very obvious, the shortcomings of the first preparation technology, the low
repetitive complex samples; Secondly because of the composite plastic phase strength below
amorphous matrix, which can lead to reduce the strength of the material in plastic, at the same
time, improve the intensity. Therefore, sacrifice to explore new improve the method of plastic
metal glass becomes necessary, here we provide three in practice feasible improve the method of
plastic metal glass.
2.1. High pressure processing improve the method of plastic metal glass
In high intensity pressure function, the material will happen irreversible structure change, this
