In situ TEM observation of the interaction of strain-induced hydride and crack propagation in Ti-6Al-4V

1987 ◽  
Vol 21 (3) ◽  
pp. 265-268 ◽  
Author(s):  
H.Z. Xiao ◽  
S.J. Gao ◽  
X.J. Wan
1998 ◽  
Vol 554 ◽  
Author(s):  
J. A. Horton ◽  
J. L. Wright ◽  
J. H. Schneibel

AbstractThe fracture behavior of a Zr-based bulk amorphous alloy, Zr-10 Al-5 Ti-17.9 Cu-14.6Ni (at.%), was examined by transmission electron microscopy (TEM) and x-ray diffraction forany evidence of crystallization preceding crack propagation. No evidence for crystallizationwas found in shear bands in compression specimens or at the fracture surface in tensile specimens.In- situ TEM deformation experiments were performed to more closely examine actualcrack tip regions. During the in-situ deformation experiment, controlled crack growth occurredto the point where the specimen was approximately 20 μm thick at which point uncontrolledcrack growth occurred. No evidence of any crystallization was found at the crack tips or thecrack flanks. Subsequent scanning microscope examination showed that the uncontrolledcrack growth region exhibited ridges and veins that appeared to have resulted from melting. Performing the deformations, both bulk and in-situ TEM, at liquid nitrogen temperatures (LN2) resulted in an increase in the amount of controlled crack growth. The surface roughness of the bulk regions fractured at LN2 temperatures corresponded with the roughness of the crack propagation observed during the in-situ TEM experiment, suggesting that the smooth-appearing room temperature fracture surfaces may also be a result of localized melting.


Author(s):  
Kang Yan ◽  
Zhongwei Chen ◽  
Wenjie Lu ◽  
Yanni Zhao ◽  
Wei Le ◽  
...  

1990 ◽  
Vol 213 ◽  
Author(s):  
A.S. Akkurt ◽  
G. Liu ◽  
G.M. Bond

ABSTRACTThe object of this study has been to gain a greater understanding of deformation and fracture processes in a Ti-24Al-11Nb (at %) alloy. The in-situ TEM deformation technique has been used to observe these processes as they occur. Material characterization studies revealed the existence of three different crystal structures in the material (α2,B2 and orthorhombic (0)). Slip is first initiated in the B2 and 0 phases. Although dislocations are observed in the α2 phase in the deformed material, they are seen only in high-stress regions and only in some laths. While numerous dislocations may be injected into the corresponding grain and phase boundaries, slip does not easily propagate into the α2 phase. Cracks are seen to originate most frequently in the regions transformed fully to α2 laths, and sometimes in the regions that contain α2 laths at prior β grain boundaries. Failure of grain or phase boundaries in the B2 or 0 phases where no α2 is present is not observed. Crack branching in the α2 phase is common, particularly in the vicinity of phase boundaries. Crack propagation in the B2 and 0 phases occurs by plastic thinning, and cracks formed in the α2 lath regions are either stopped in phase boundaries or blunted in the neighboring 0 or B2 grains.


2011 ◽  
Vol 65 (5) ◽  
pp. 377-379 ◽  
Author(s):  
Hongtao Wang ◽  
Anmin Nie ◽  
Jiabin Liu ◽  
Peng Wang ◽  
Wei Yang ◽  
...  

2006 ◽  
Vol 54 (2) ◽  
pp. 435-443 ◽  
Author(s):  
Yong Zhong ◽  
Furen Xiao ◽  
Jingwu Zhang ◽  
Yiyin Shan ◽  
Wei Wang ◽  
...  

2010 ◽  
Vol 59 (S1) ◽  
pp. S61-S66 ◽  
Author(s):  
P. J. Shang ◽  
Z. Q. Liu ◽  
D. X. Li ◽  
J. K. Shang

2011 ◽  
Vol 37 (2) ◽  
pp. 647-650 ◽  
Author(s):  
Y.G. Liu ◽  
D.C. Jia ◽  
Y. Zhou ◽  
M.H. Fang ◽  
Z.H. Huang

Author(s):  
Charles W. Allen

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.


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