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The microstructures of β solution treated and cooled Ti-6Al-4V specimens were Widmanstätten α plate structures for furnace cooling and air cooling, whereas martensite structure was obtained for water-quenching. In each case, the β matrix was partially retained alter cooling at room temperature. The initial structures after isothermal holding at deformation temperature were (α + β) lamellar structures formed by the growth of β matrix between α plates.

In this paper, the results of a study on microstructural influences on mechanical behavior of the high-strength alloy steel Tenax™ 310 are presented and discussed. Under the influence of fully reversed strain cycling, the stress response of this alloy steel revealed softening from the onset of deformation. Cyclic strain resistance exhibited a linear trend for the variation of both elastic strain amplitude with reversals-to-failure, and plastic strain amplitude with reversals-to-failure. Fracture morphology was essentially the same at the macroscopic level over the entire range of cyclic strain amplitudes examined. However, at the fine microscopic level, this high-strength alloy steel revealed fracture to be mixed-mode with features reminiscent of “locally” ductile and brittle mechanisms. The macroscopic mechanisms governing stress response at the fine microscopic level, resultant fatigue life, and final fracture behavior are presented and discussed in light of the mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents during fully reversed strain cycling, cyclic strain amplitude, and resultant response stress.

In this study effects of small amount of yttrium addition on grain growth of C.P titanium (single α), Ti-14Mo-3Nb-1.5Zr (single β) and a newly developed Ti-4.5Al-6Nb-2Mo-2Fe (α+β) titanium alloy are investigated. By adding yttrium nano-sized Y2O3 particles are formed in 'in-situ' mode. These particles lead to significant suppression of grain growth in single α and β alloys rather than in the α+β alloy. The results are discussed with regard to conventional grain growth and grain boundary pinning models. It is concluded that yttrium is a potential micro alloying element in titanium alloys and could be used as a grain refining agent.

Recrystallization and partial re-melting processes have been developed for producing semi-solid feedstock in a solid state in which a globular microstructure is obtained by plastic deformation followed by reheating. In this research, to induce strain, a cast- and solution-treated Aluminum A356 (7 wt pct Si) alloy was subjected to a repetitive equal channel angular pressing process using a 90 deg die, up to a total accumulated strain of approximately 8 in route A (increasing strain through a sequence of passes with no rotation of the sample after each pass) at ambient temperature. The microstructural evolutions of deformed and reheated materials were studied by optical microscopy, scanning electron microscopy, and electron back-scattered diffraction analysis. In addition, the influences of pre-deformation on the recrystallization mechanism and liquid formation of A356 alloy were presented and discussed. The results are also supported by differential thermal analysis experiments. Evaluation of the observations indicated that the average cell boundary misorientation increased with increasing strain, so this increased misorientation accelerated the mobility of boundaries and recrystallization kinetics. Therefore, the recrystallization mechanism and kinetics affected by deformation, reheating condition, and intrinsic material properties determined the particle size in the semi-solid state.