Strength microstructure

Aluminium and magnesium melt at just over 900 K. Room temperature is 0.3 T and 100°C is 0.4 T, . Substantial diffusion can take place in these alloys if they are used for long periods at temperatures approaching 80-100°C. Several processes can occur to reduce the yield strength loss of solutes from supersaturated solid solution, overageing of precipitates and recrystallisation of cold-worked microstructures. 

Describe briefly how the tensile strength of ceramic materials is determined by their microstructures. How may the tensile strength of ceramics be improved ... 

The variability in fracture stress when small artificial flaws were controlling strength was particularly pronounced for H-451 graphite, as can be seen in Fig. 12. Here the crack dimensions and crack trip process zone dimensions are comparable to the microstructural dimensions. Consequently, local variations in microstmeture... 

Most materials scientists at an early stage in their university courses learn some elementary aspects of what is still miscalled strength of materials . This field incorporates elementary treatments of problems such as the elastic response of beams to continuous or localised loading, the distribution of torque across a shaft under torsion, or the elastic stresses in the components of a simple girder. Materials come into it only insofar as the specific elastic properties of a particular metal or timber determine the numerical values for some of the symbols in the algebraic treatment. This kind of simple theory is an example of continuum mechanics, and its derivation does not require any knowledge of the crystal structure or crystal properties of simple materials or of the microstructure of more complex materials. The specific aim is to design simple structures that will not exceed their elastic limit under load. 

Precipitate microstructures are important for the strength and hardness of many alloys [196-210]. A number of experimental [211-228] and theoretical [220,229-247] investigations have shown that the development of precipitate morphologies is influenced by elastic interactions (El) resulting from a lattice misfit between matrix and precipitates and from an externally applied elastic strain. 

Most materials, be they natural or synthetic, have limited utility. However, technical ingenuity has increased the utility of these materials beyond anyone s wildest imagination. The enormous range of steel that can be produced by adding carbon or other elements to give it the required balance of properties, such as strength and hardness, related to changes in their microstructure [1-3] is just one example. 

The amorphous orientation is considered a very important parameter of the microstructure of the fiber. It has a quantitative and qualitative effect on the fiber de-formability when mechanical forces are involved. It significantly influences the fatigue strength and sorptive properties (water, dyes), as well as transport phenomena inside the fiber (migration of electric charge carriers, diffusion of liquid). The importance of the amorphous phase makes its quantification essential. Indirect and direct methods currently are used for the quantitative assessment of the amorphous phase. 

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