| In this thesis, the heat burst method was used to compose TiAl and TiAl(Nb,B)based alloy powder, the spark plasma sintering (SPS) technology was used to fabricate Ti2AlC/TiAl in-situ reaction composites. Ti2AlC/TiAl(Nb,B)composites were heated by the method of heating heat treatment. Through the research on MATLAB image toolbox, we get suitable image processing software of Ti2AlC/TiAl composite SEM images .Based on fractal theory, the procedure of box counting dimension and multi-fractal spectrum are obtained with MATLAB platform, and then we calculate the relationship between macro properties and the fractal dimension.With the discrete cosine transform, histogram, wiener filtering, edge detection, threshold segmentation, corrosion and expansion, the images get further compression, the pixel values distributed more uniformly, more noise in images are remove, and then we extract the key part of the SEM picture. At last the SEM images are changed to binary images.The fracture dimension is calculated by MATLAB through analysis the box counting dimension theory of simple fractal. The fractural characteristic is displayed at the fracture and surface of Ti2AlC/TiAl composites. For different Ti2AlC composite materials with the different treatment, different fractal dimension of the images would be obtained from their SEM images. So samples can be distinguished with fractal dimensionThe more detailed fractal grids is divided to, the smaller fractal dimension is, the more accurately fractal dimension calculate. The fracture dimension of the sample with element B is larger than that of the sample without one. That is because the old balance is broken, a slight change of material is amplified, and then the random and tiny fluctuation brings about new stable state. Fractal dimension can reflect these changes very well.The Ti2AlC composite materials show the characteristics of ductility after heat treatment. The fractal dimension of the samples enhance with the increase of the fracture toughness and bending strength of the material, which is accord with the characteristics of brittle materials. With the decrease of the fractal dimension, the fracture toughness and bending strength increases at low temperature. The surface of Ti2AlC/TiAl composite material transfer more complexity result of theα2/γcrystalline cluster changing thicker. That is make the fracture dimension turn larger and largerA quality relationship has been obtained between the fractal dimension and fracture toughness, bending strength. Then the sample can be distinguished by the calculation of the fractal dimension, and we can analysis quantitative the mechanical properties of materials via the analysis of SEM images.The parameter is calculated by MATLAB through analysis the multi-fractal spectrum theory. Without r=0.00625, giving rise to the small fluctuate, lnχq(r) and lnr shows the well linear relationship in spite of the value of q.τ(q) and q show good linear relationship in1403K after the rapid heat treatment with correlation coefficient reached 99.99%. D (q) and q turn to be gently, and the fracture appears uniformity. SEM image belong to single fractural.τ(q) and q show nonlinear relationship result in the protuberance existed in q∈[-3,-1], D(q) and q turn to be more steep, at last the clock shape relationship between theαand f(α) reveal the good symmetry of spectrum, uneven distribution of the fracture, multi-fractal feature clearlyWe use the MATLAB texture filter to process the material surface texture segmentation, and set up the three-dimensional structure of SEM images. So the hole sharp can be observed clearly.
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