Papers by Keyword: Lamellar Spacing

Abstract: Ti-6Al-4V alloy is not easy to machine complicated shapes due to its low thermal conductivity, so high-temperature forming techniques such as ring-rolling are being applied. When this high-temperature forming technology is applied, the microstructure is greatly changed by process variables, and the mechanical properties of the forming product are also different accordingly. In particular, in the case of the Widmanst tten structure, α lamellar spacing and colony size have a great influence on mechanical properties. Therefore, in this study, the most suitable process conditions were selected by performing a high-temperature compression test to apply the ring-rolling process to the Ti-6Al-4V alloy used as an aerospace material. After that, the microstructure of the forming product was observed, the effects of α lamellar spacing and colony size on the mechanical properties were confirmed, and the correlation between mechanical properties and microstructure was evaluated based on this.

Abstract: Study of grain size and lamellar spacing on fatigue crack propagation resistance in TiAl alloy has been done. The effects have been analyzed specifically. Meanwhile, the influence has been verified with some fatigue crack propagation experimental results and Paris formula. The experimental results confirmed that the grain size and lamellar spacing have significant effect on fatigue crack growth resistance. According to the Paris formula, the specific values of the constants in the formula were calculated.

Abstract: Solidification of Zn-5wt%Al alloy was investigated by DTA and quantitative metallography analysis. The effect of cooling rate on eutectic lamellar spacing was studied. Based on analysis of heat transfer during solidification, relation between cooling rate and eutectic lamellar was derived. Curve fitting was carried out according to the data of experiment. The results indicate that eutectic lamellar spacing is approximately inverse ratio with the one fourth power of cooling rate.

Abstract: The article presents the results of optical microscopy, scanning electron microscopy (SEM), Transmission Electron Microscope (TEM) conducted on a Ti–46.5Al–2.5V-1.0Cr–0.3Ni alloy before and after different heat treatments. Heat treatment of the alloy at 1340°C followed by cooling leads to the formation of the fully lamellar microstructure which consists of γ lamellae mostly and of small amount of α2 lamellae. The cooling rate of 50°C/min in alloy tcx1-G produced an optimal microstructure. This cooling rate generated finest lamellae with the smallest individual lamella spacing among the alloys.