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Effects of trace TiB2 on solidification microstructure of Ti-6Al-4V alloy were investigated. The result shows that the microstructure of the ingot was refined by the added TiB2. The grain size and α lath size were reduced gradually with the increase in TiB2. The grain size is reduced by about an order of magnitude with an addition of 0·96 wt-%TiB2, and the dendrite appears in the ingot. Such a tendency is similar to the change of the microstructure with boron addition. Ti-6Al-4V-B phase diagram and growth restriction factor Q are applied to analyse the influence mechanism of trace TiB2 on the microstructure. [ABSTRACT FROM AUTHOR]

The microstructure, ordering parameter, and magnetic properties of multilayer [FePt(x)/Os]n films on glass substrate by dc-magnetron sputtering (with x being thickness in nm; Os with a fixed thickness 5 nm; n being the number of layers) have been studied as a function of the annealing temperatures between 300 and 900 °C. The grain size of multilayer films can be controlled by annealing temperature and thickness of the FePt layer with Os space layer. The coercivity as a function of the annealing temperature for samples with n = 1 and pure FePt behaves roughly saturated after annealing above 700 °C. However, for samples with n > 4 the value of Hc seems still increasing with increasing annealing temperature between 600 and 900 °C, and the ordering parameter decreases with increasing the number of Os layers. Our experimental results are reasonably well to describe the effect of strain-assisted transformation. [ABSTRACT FROM AUTHOR]

Hot deformation behavior of high Nb containing TiAl based alloy with a nominal composition of Ti-44Al-8Nb-0.2W-0.2B-0.1Y at 1225 °C and 1275 °C is investigated. The deformation mechanism of α phase is dynamic recovery at 1275 °C, whereas γ phase is mainly dynamic recrystallized. It is revealed that α phase is softer and easier to be deformed when the alloy is deformed at 1275 °C. The reasons of the different deformation behavior between 1225 °C and 1275 °C, as well as the different deformation behavior between α phase and γ phase are analyzed. A multistep deformation process at gradually lowered temperature is proposed to eliminate the adverse influence of remnant lamellar structure on mechanical properties. [ABSTRACT FROM AUTHOR]

For the first stage, a metastable β titanium alloy, Ti-3.5Al-5Mo-4V-2Cr-2Sn-2Zr-1Fe reinforced with trace amounts of TiB whiskers and TiC particles was fabricated by vacuum arc melting process and hot forging followed by heat treatment at 780 °C/740 °C, then by aging at 500 °C, 550 °C, 570 °C and 600 °C. For the second stage, the unreinforced titanium alloy was also fabricated by the same process. The microstructural characteristics were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Traces of TiB whiskers and TiC particles (2.2 vol.%) with a volume ratio of 2:3 synthesized in situ exerted a hybrid reinforcing effect on the β titanium alloy. The reinforcements were uniformly distributed in the matrix and the elastic modulus was improved about 25 GPa. Ultimate tensile strength and yield strength achieves about 1625 MPa and 1500MPa respectively, with ductility at 7% when the aging temperature is 500 °C. The ductility of (TiB + TiC)/(Ti-3.5Al-5Mo-4 V-2Cr-2Sn-2Zr-1Fe) matrix composite could be enhanced by increasing the aging temperatures. After 780 °C followed by aging at 570 °C, excellent strength and plasticity properties were obtained (ultimate tensile strength of matrix alloy is 1350 MPa with elongation of 18% and ultimate tensile strength of composite is 1500 MPa with elongation of 13%). [ABSTRACT FROM AUTHOR]