Transcrystalline fracture

Many process parameters are responsible for transcrystallinity." The most extensive transcrystallinity is observed under rapid pulling of fibers and high cooling rates. Other parameters include the viscosity of the polymer melt, the rate of shear, the fiber/matrix wettability, and the temperature gradient between matrix and fiberFigure 10.15 shows the effect of interlayer thickness on the fracture en-... 

In Al-Zn-Mg-Cu alloys alloyed only with Fe, fracture had a mixed character it was ductile and semibrittle, transcrystalline with the formation of pores around the spherical second phase particles. The plasticity of these alloys was EL = 13-20 % depending on the content of Fe. As was shown by X-ray microanalysis, the phase that is situated in dimples and has spherical form contains Zn, Mg, Cu, and Fe. 

Microstmctural studies on the above samples determined that the addition ofYaOa or MgO caused a transition from a transcrystalline to intercrystalline fracture. This transition was due to softening of the glassy phase, which resulted in slow crack growth at low stress levels. 

The decrease of tensile strength and the increase of reduction in area with increasing test temperature can be related to changes in the fracture mode (Fig. 3.1-163), i. e., cleavage fracture, brittle grain boundary failure, and ductile transcrystalline failure [1.158]. 

In most cases, shear fracture is transcrystalline (through the grains), but, depending on the material state, intercrystalline fracture (fracture along the grain boundaries) may also occur. 

As a consequence of the above mentioned effects, but in contrast to many other metallic materials, the fracture toughness of Mo and W is strongly reduced with increasing degree of recrystallization. With increasing plastic deformation, the fracture toughness increases (see Sect. 3.1.9.4), combined with a transition from intercrystalline to transcrystalline cleavage and to a transcrystalline ductile fracture [1.147,158,159]. 

Cracking or fracturing that occurs through or across a crystal or grain. Also called transcrystalline cracking. Contrast with intergranular cracking. 

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