Topic
Fractography
About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.
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TL;DR: In this paper, critical flaws were determined by fractography in several ceramic bodies having internal stresses due to thermal expansion anisotropy, phase transformations, or second phases, and the projected contribution of internal stresses to failure was consistent with simple estimates of their levels as the flaw size decreases to about the grain size.
Abstract: Critical flaws were determined by fractography in several ceramic bodies having internal stresses due to thermal expansion anisotropy, phase transformations, or second phases. Fracture energies calculated using the observed flaw sizes and shapes agreed well with those measured by fracture-mechanics techniques at large flaw sizes. However, at smaller flaw sizes, calculated fracture energies decreased with decreasing flaw size. This decrease is attributed to internal stresses which increasingly contribute to failure as flaw sizes approach the sizes dominated by tensile components of these internal stresses. These components, in turn, are due to statistical variations of grain orientation. The projected contribution of internal stresses to failure is consistent with simple estimates of their levels as the flaw size decreases to about the grain size. Thus, application of fracture mechanics must take into account an increasing contribution of internal stresses as flaw sizes decrease in bodies in which these stresses can exist.
60 citations
TL;DR: In this paper, Inconel 625 claddings with low base metal dilution possessed better wear resistance as compared to those with high levels of dilution, which resulted in narrowing of the fusion boundary zone.
60 citations
TL;DR: In this paper, a CA glass-ceramic joining and seal coating was applied to the Hi-Nicalon™ SiC fiber-reinforced SiC matrix composites in which the matrix had been formed through chemical vapor infiltration and polymer impregnation and pyrolysis methods.
60 citations
TL;DR: In this paper, the failure due to complete fracture of the struts on porous Ti is controlled primarily by macro-pores, and the failure mechanism has been discussed by taking the intrinsic microstructural features into consideration.
60 citations
TL;DR: In this paper, the Ni-Ti alloys subjected to hydrogen charging of 1 or 10 A/m2 for 24 or 120 hours, respectively, were arranged using an electrochemical system and the hardness numbers in the cross-sectional area of the alloy and the amount of evolved hydrogen were determined.
Abstract: A nickel-titanium superelastic alloy is susceptible to environmental embrittlement in a corrosive atmosphere. Because a delayed fracture of the alloy is associated with hydrogen absorption and subsequent formation of brittle hydride phases, the diffusion rate of hydrogen is thought to be one of the factors determining its service life. The Ni-Ti alloys subjected to hydrogen charging of 1 or 10 A/m2 for 24 or 120 hours, respectively, were arranged using an electrochemical system. Both the hardness numbers in the cross-sectional area of the alloy and the amount of evolved hydrogen were determined. The fracture surface of the alloys, under tension, was observed using a scanning electron microscope (SEM). Theoretical distributions of the hydrogen concentration were computed for an infinite cylinder model using the differential equation of diffusion. The diffusion constant of hydrogen through the alloy is estimated to be 9×10−15 m2/s, assuming that the hardness is proportional to the concentration of hydride and/or hydrogen. Experimental results of the hardness measurements and fractography support the estimated diffusion constant. The process of fracture formation in a biological corrosive environment was discussed. It was concluded that galvanic currents and fretting corrosion of the alloy might be effective factors in fracture formation during function.
60 citations