Crack Growth in Metal-Ceramic Composites

2000 ◽  
Author(s):  
Parul Agrawal ◽  
C. T. Sun
Keyword(s):  
Residual Stresses ◽  
Crack Growth ◽  
Crack Path ◽  
Ceramic Composites ◽  
Fracture Mechanisms ◽  
Environmental Scanning ◽  
Metal Ceramic ◽  
Bend Tests ◽  
Point Bend

Abstract This research focuses on the fracture mechanisms in various metal-ceramic composites. The objective was to study the effects of volume fractions, residual stresses and other microstructural features like particle size and contiguity of the constituent phases, on fracture. Neutron diffraction tests were performed to measure residual stresses in these composites. In-situ 3-point bend tests were performed inside the ESEM (Environmental scanning electron microscope) chamber to observe crack growth. It was found that residual stresses and contiguity play dominant roles in fracture and defining the crack path. The correlations between residual stresses and other microstructural features with the crack path and failure mechanisms were established based on experimental observations.

scholarly journals Preparation of metal–ceramic composites by sonochemical synthesis of metallic nano-particles and in-situ decoration on ceramic powders

2016 ◽  
Vol 31 ◽  
pp. 417-422 ◽  
Author(s):  
A. Poulia ◽  
P.M. Sakkas ◽  
D.G. Kanellopoulou ◽  
G. Sourkouni ◽  
C. Legros ◽  
...  
Keyword(s):  
Ceramic Composites ◽  
Nano Particles ◽  
Ceramic Powders ◽  
Sonochemical Synthesis ◽  
Metal Ceramic

Characterization of the Residual Stresses and Strength of Ceramic-Metal Braze Joints

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Matteo Galli ◽  
John Botsis ◽  
Jolanta Janczak-Rusch ◽  
Gerd Maier ◽  
Udo Welzel
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Finite Element Models ◽  
Plastic Response ◽  
X Ray Diffraction ◽  
Elastoplastic Properties ◽  
Bend Tests ◽  
Point Bend ◽  
Good Agreement

Residual stress relief in ceramic-metal joints produced by active brazing depends primarily on the plastic response of the filler metal. A procedure for the production and mechanical characterization of bulk active filler alloy specimens is developed. In parallel ceramic-metal joints are produced and tested. Residual stresses are measured by X-ray diffraction while the joint strength is assessed by four-point bend tests. The obtained elastoplastic properties of the filler are introduced into finite element models to predict the residual stresses in the joints and their behavior in bending. The results of the simulations show good agreement both with the residual stress measurements and with the results of four-point bend tests.

Effect of Deformation Processing on Mechanical Properties of Nb-10 a/o Si In-Situ Composite

1993 ◽  
Vol 322 ◽  
Author(s):  
I. Weiss ◽  
M. Thirukkonda ◽  
R. Srinivasan
Keyword(s):  
Fracture Toughness ◽  
Thermomechanical Processing ◽  
Cast Alloy ◽  
Extrusion Direction ◽  
Microstructural Refinement ◽  
In Situ Composite ◽  
Size Refinement ◽  
Bend Tests ◽  
Point Bend

AbstractNb-10 a/o Si alloy is an in-situ composite. The microstructure of the cast alloy consists of pro-eutectic Nb dendrites distributed in a matrix of eutectic Nb3Si + Nb phases. The microstructure of the as-cast alloy was modified by multiple hot extrusions producing an oriented composite. Extensive grain size refinement occurred in both the Nb and Nb3Si phases. The ductile primary (pro-eutectic) Nb particles were aligned along the extrusion direction. Bend strength and fracture toughness measured by three point bend and four point bend tests, respectively, showed that both the yield strength and fracture toughness of the alloy increases considerably following this thermomechanical processing. These improvements have been attributed to the changes in size, morphology and spacing of the constituent phases and their microstructural refinement.

scholarly journals Computational analysis of deformation and fracture in composite materials and coatings

2019 ◽  
Vol 221 ◽  
pp. 01017
Author(s):  
Ruslan Balokhonov ◽  
Rustam Bakeev ◽  
Varvara Romanova ◽  
Evgenia Emelianova ◽  
Maksim Sergeev ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Computational Analysis ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Ceramic Composites ◽  
Isotropic Hardening ◽  
Ceramic Particles ◽  
Deformation And Fracture ◽  
Metal Ceramic ◽  
Composite Microstructure

Deformation and fracture of metal-ceramic composites and coatings under quasistatic tension, compression, shear, and during cooling from the melt to room temperatures are numerically investigated. Dynamic and quasistatic boundary-value problems are solved in twoand three-dimensional formulations by the finite-difference and finite-element methods. Constitutive models include the isotropic hardening of aluminum and fracture of ceramic particles. Composite microstructure is taken into account explicitly. Analysis of the fracture in composites is carried out, with the residual stresses being not taken into consideration. Origination of cracks in the near-interface regions of bulk tension and their propagation in ceramic particles are investigated. Residual stresses formed during cooling of the composites are calculated for different volume fractions of particles.

Metal-ceramic composites via in-situ methods

1997 ◽  
Vol 68 (2) ◽  
pp. 132-155 ◽  
Author(s):  
B.S.S. Daniel ◽  
V.S.R. Murthy ◽  
G.S. Murty
Keyword(s):  
Ceramic Composites ◽  
Metal Ceramic ◽  
In Situ Methods

Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

2008 ◽  
Author(s):  
Julian K. Benz ◽  
J. H. Kim ◽  
Ronald G. Ballinger
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Crack Growth ◽  
Oxygen Concentration ◽  
Crack Path ◽  
Fatigue Loading ◽  
Effect Of Oxygen ◽  
Static Conditions

The effect of oxygen partial pressure on fatigue and SCC growth rates in alloy 617 has been studied using both static and fatigue loading @ 650°C over the oxygen partial pressure range 10−19–10−2 atm. Tests were conducted at either constant stress intensity factor, K, for static conditions or constant ΔK in fatigue. Oxygen concentration was measured on both the inlet and outlet as well as in-situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular and exhibited an increasing crack growth rate with decreasing oxygen concentration.

Displacement Reactions in the Ni-Al-O System Resulting in Periodic Layer Structures

1994 ◽  
Vol 365 ◽  
Author(s):  
Daniel W. Song ◽  
Ramesh Subramanian ◽  
RÜdiger Dieckmann
Keyword(s):  
Reaction Mechanism ◽  
Periodic Structures ◽  
Ceramic Composites ◽  
Processing Technologies ◽  
Layer Structures ◽  
Metal Ceramic ◽  
Displacement Reactions ◽  
Periodic Layer ◽  
In Situ Processing

ABSTRACTDisplacement reactions may play an important role in in situ processing technologies for the production of metal-ceramic composites. To better understand such reactions displacement reactions between NiO and Al were studied at high temperatures. Different reaction layers with periodic structures were observed involving Al2O3, Al3Ni, Al3Ni2, Ni and Al. The experimental observations are presented and discussed with regard to the reaction mechanism.

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