Volume fraction

About: Volume fraction is a research topic. Over the lifetime, 16312 publications have been published within this topic receiving 374181 citations.

Microstructural study of transient liquid phase bonded cast INCONEL 738LC superalloy

Abstract: The microstructure of the transient liquid phase (TLP) bonded joint of a cast INCONEL 738LC superalloy, made with a commercial Ni-Cr-B filler alloy, Nicrobraz 150, was examined by analytical scanning and transmission electron microscopic techniques. Due to incomplete isothermal solidification at the bonding temperature, the residual liquid interlayer transformed to nonequilibrium eutectic microconstituents consisting of chromium-rich M5B3, nickel-rich M23B6, and nickel-based γ solid solution phases. Also, a significant volume fraction of complex fcc Cr-Mo-W rich carboborides was observed in the joint/base alloy interface region. This is contrary to the predictions of the currently available TLP models that predict a precipitate-free joint/base alloy interface. It is suggested that solid-state diffusion of boron prior to completion of equilibration process induced the formation of carbo-boride phase, which needs to be adequately considered to develop an optimum postbraze heattreatment process to produce a joint with optimum properties.

Mechanisms of Topologically Close-Packed Phase Suppression in an Experimental Ruthenium-Bearing Single-Crystal Nickel-Base Superalloy at 1100 °C

Abstract: Ruthenium (Ru) suppresses the precipitation of deleterious topologically close-packed (TCP) phases in high refractory content single-crystal Ni-base superalloys. The effectiveness of Ru as a TCP suppressant appears to be the net effect of its limited solubility in the TCP phase, a lower density of structural growth ledges for atomic attachment at the TCP/matrix interface, and destabilization of the γ′ phase at elevated temperatures. These characteristics combine to limit the growth rates of precipitates and decrease the driving force for TCP precipitation, which has the secondary effect of reducing the TCP nucleation rate. The reduction in γ′ volume fraction upon the addition of Ru is particularly potent due to the sensitivity of the rhenium (Re) content in the γ matrix to changes in the γ′ volume fraction.

Functionally-graded fiber-reinforced cement composite: Processing, microstructure, and properties

Abstract: A functionally-graded material system has been developed with a spatially tailored fiber distribution to produce a four-layered, functionally-graded fiber-reinforced cement composite (FGFRCC). Fiber volume fractions were increased linearly from 0% in the compression zone to 2% in the tensile zone so that more fibers were available to carry tensile stress in a bending beam experiment. Extrusion was used to produce single homogeneous layers of constant fiber volume fraction and highly oriented fibers. The FRCC layers with different fiber volume fractions were stacked according to the desired configuration and then pressed to produce an integrated FGFRCC. Polished cross-sections of the FGFRCC were examined using a scanning electron microscope (SEM) to measure the fiber distribution. Flexural tests were carried out to characterize the mechanical behavior and to evaluate the effectiveness of the designed fiber distribution. No delamination between layers was observed in the fractured specimens. Compared to homogeneous FRCC with the same overall fiber volume fraction, the FGFRCC exhibited about 50% higher strength and comparable work of fracture.