The thin section consists of angular shaped grains with µm to mm size. The grains are in contact to each other and show different colors. The boundaries between the grains have a sharp differentiation. The starting deformation process leads to a transport of the grains in south east direction (highest pressure direction) of the thin section. Through this process the grains start to move and change their form. Some grain boundaries begin to blend with other boundaries and as a result the grains get bigger. Smaller grains in the thin section get “eaten” from the big ones and disappear completely in the big grains. The grain size is changing in bigger shape. The different thin section particles are moving through the picture and show that the boundaries are changing like a fluid through the deformation process. During the progressive time the grain size gets always bigger (most grains show a mm size) because through the deformation process more and more grains get “eaten” by the big ones. [...]
Table Of Contents
I. Description of the microstructural development
II. Deformation methodic with aid of marker particles
III. Development of the deformation tensor
IV. Deformation tensor with a Mohr-cycle
V. Deformation rate vertical to the main stress field
VI. References
I. Description of the microstructural development
The thin section consists of angular shaped grains with µm to mm size. The grains are in contact to each other and show different colors. The boundaries between the grains have a sharp differentiation. The starting deformation process leads to a transport of the grains in south east direction (highest pressure direction) of the thin section. Through this process the grains start to move and change their form. Some grain boundaries begin to blend with other boundaries and as a result the grains get bigger. Smaller grains in the thin section get “eaten” from the big ones and disappear completely in the big grains. The grain size is changing in bigger shape. The different thin section particles are moving through the picture and show that the boundaries are changing like a fluid through the deformation process. During the progressive time the grain size gets always bigger (most grains show a mm size) because through the deformation process more and more grains get “eaten” by the big ones (Fig.1).
illustration not visible in this excerpt
Fig. 1: The red cycle shows how a big grain (blue) flows around another smaller grain (black) and “eats” this. This process shows the development of a new big grain.
The grain boundaries at several grains illustrate that the boundaries aren’t so close to each other as in the beginning of the deformation process (Fig. 2a). During the time the space grows between the grains (Fig. 2b). In some deformation processes there is sub-grain development but in this experiment you can’t see any sub-grain development during the entire deformation part. Next to these deformation modifications there is also a change in the grain shape. At the beginning of the experiment the shape of the grains are angular and regular. During the continually deformation the pattern of the grains changed. They don’t have a regular and angular form anymore. They look like unregularly, disintegrated pattern (patch blanket) after deformation time, as written above, the grain boundaries don’t fit exactly together: They show a “gap” between the grains.
illustration not visible in this excerpt
Fig. 2a+b: The left picture (2a) shows that the grain boundaries are in contact to each other (green line and cycle). The right picture (2b) shows that the grain boundaries have space between the different grains (green cycle and line show the space “gap” between the grains).
II. Deformation methodic with aid of marker particles
The marker particles are the small black dots in the thin section. They help to identify the deformation and the deformation tensor. These particles get moved through the deformation process, so some of them get lost when the grains get “eaten”. They show also the rotation component of the grains. With the aid of these particles the deformation tensor is constructed. In the following part the construction of this tensor is described.
At first a reference point has to be chosen. It is the best to take a marker particle which is good to identify through the whole series of the deformation process. After that some other points, which are also marker points, get chosen to construct the deformation tensor (Fig. 3). If the points are marked on the first picture, the other ones of this deformation experiment are downloaded in PowerPoint. You can use also other computer programs to construct a basic framework in order to get the tensor for example ArcGis or any other photo shop program. This exercise is done with PowerPoint. The reference point and some other points have to be marked on the first picture of the series. After that the following pictures of the deformation experiment are downloaded (every picture gets one slide). If this is finished the reference point is copied in every slide on the same point. When this step is finished the pictures of the deformation process get moved to the reference point so that every single picture stays always on the same reference (Fig.4).
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- Citar trabajo
- Amalia Aventurin (Autor), 2013, Grain boundary migration and the determination of strain rates, Múnich, GRIN Verlag, https://www.grin.com/document/272600
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X.