The Effect of Filler-Volume Fraction on Crack-Propagation Behavior of Particulate Composites

1981 ◽  
Vol 15 (1) ◽  
pp. 41-54 ◽  
Author(s):  
P.S. Theocaris ◽  
G.C. Papanicolaou ◽  
G.A. Papadopoulos
Keyword(s):  
Crack Propagation ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Filler Volume Fraction ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

The Role of Intermetallic Phases in Fatigue Crack Propagation Behavior of Al-Zn-Mg-Cu Alloys

2007 ◽  
Vol 555 ◽  
pp. 553-558 ◽  
Author(s):  
M. Vratnica ◽  
Z. Cvijović ◽  
K. Gerić ◽  
Zijah Burzić
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Volume Fraction ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior ◽  
Cu Alloys ◽  
Crack Propagation Behavior

The aim of the present work is to determine the role of intermetallic (IM) phases in the fatigue crack propagation behavior of hot-forged Al-Zn-Mg-Cu alloys in T73 condition. To generate differences in the volume fraction and coarseness of various IM particles, the (Fe+Si) impurity level is varied from 0.23 to 0.37 mass%. The fatigue crack propagation tests are conducted in air at ambient temperature and a stress ratio R of 0.1. Characterization of the fatigue fracture surfaces is performed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Quantified IM particles data for each alloy are then related to the fatigue properties and fractographic analysis results. It was found that almost all particles of the Fecontaining phases (primarily (Cu,Fe,Mn)Al3 and Al7Cu2Fe) are broken and not effective in hindering fatigue crack propagation. On the other hand, the Mg2Si and soluble phase particles smaller than those of the Fe-containing phases contribute beneficially to fatigue life. These particles increase the tortuosity of the crack path and retard the crack growth rate. The crack growth rate decreases as the volume fraction of coarse Fe-containing particles increases, because more secondary cracks are produced decreasing the effective stress intensity at the main crack tip.

Microstructural Effect on Crack Propagation Behavior of Ceramic Tool Materials via Cohesive Zone Modeling

2016 ◽  
Vol 836-837 ◽  
pp. 462-467
Author(s):  
Zuo Li Li ◽  
Jun Zhao ◽  
Fu Zeng Wang ◽  
An Hai Li ◽  
Xian Hua Tian
Keyword(s):  
Grain Size ◽  
Crack Propagation ◽  
Cohesive Zone ◽  
Volume Fraction ◽  
Secondary Phase ◽  
Ceramic Tool ◽  
Zone Method ◽  
Tool Materials ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

A systematic and parametric study of the effect of grain size and volume fraction of secondary phase on crack propagation behavior of Al2O3 based ceramic tool materials was carried out. Two-dimensional centroid V toughness oronoi tessellations were generated with random grain orientations. Cohesive Zone Method (CZM) was utilized to simulate crack propagation behavior. Zero-thickness cohesive elements were embedded on grain boundaries and inside grains. Crack initiation and propagation in ceramic tool materials microstructure were simulated without predefined crack. Simulation results revealed that crack initiated at the maximum stress position and propagated along the direction perpendicular to external load. Decreasing the grain size or increasing the volume fraction of secondary phase can improve the fracture stress of Al2O3 ceramic tool materials.

scholarly journals Crack Propagation Behavior of a Ni-Based Single-Crystal Superalloy during In Situ SEM Tensile Test at 1000 °C

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1047
Author(s):  
Wenxiang Jiang ◽  
Xiaoyi Ren ◽  
Jinghao Zhao ◽  
Jianli Zhou ◽  
Jinyao Ma ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Tensile Test ◽  
Single Crystal ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Single Crystal Superalloy ◽  
Propagation Path ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

An in situ scanning electron microscope (SEM) tensile test for Ni-based single-crystal superalloy was carried out at 1000 °C. The stress displacement was obtained, and the yield strength and tensile strength of the superalloy were 699 MPa and 826 MPa, respectively. The crack propagation process, consisting of Model I crack and crystallographic shearing crack, was determined. More interestingly, the crack propagation path and rate affected by eutectics was directly observed and counted. Results show that the coalescence of the primary crack and second microcrack at the interface of a γ/γ′ matrix and eutectics would make the crack propagation rate increase from 0.3 μm/s to 0.4 μm/s. On the other hand, crack deflection decreased the rate to 0.05 μm/s. Moreover, movement of dislocations in front of the crack was also analyzed to explain the different crack propagation behavior in the superalloy.

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