Dislocation structures in zirconium and zircaloy-4 fatigued at different temperatures

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0232-1· OSTI ID:484851

Xiao, L; Gu, H ^[1]

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1. Xi`an Jiaotong Univ. (China). Research Inst. for Strength of Materials

The development of characteristic dislocation structures in pure zirconium and zircaloy-4 fatigued under pull-push strain control as the testing temperature and the cycle strain range varied was examined using a thin-foil transmission electron microscopy (TEM) technique. The slip planes and the twinning planes were determined by a standard stereographic trace analysis technique. The first-order prismatic slip {l_brace}10{bar 1}0{r_brace}, is the primary deformation mode in zirconium and zircaloy-4 fatigued from room temperature (RT) to 873 K. The pyramidal slip {l_brace}{bar 1}2{ovr 11}{r_brace} is activated at 673 K and at high cyclic strain ranges, whereas the basal slip {l_brace}0001{r_brace} only appears in those specimens fatigued at 873 K. The {l_brace}10{bar 1}2{r_brace}, {l_brace}11{bar 2}1{r_brace}, and {l_brace}11{bar 2}2{r_brace} types of twins were detected in specimens fatigued at RT. Twinning becomes less frequent as the testing temperature increases. The schematic map of the cyclic deformation modes as a function of the plastic strain range and the test temperature is described. The dislocation configurations in fatigued pure zirconium specimens evolve from a planar arrangement to a cell structure as the test temperature and the strain range increase. For zircaloy-4, the fatigued dislocation structure is parallel dislocation bands at 873 K, respectively. Finally, the fatigued dislocation-structure evolution map with the cyclic strain range and the test temperature are qualitatively established for zirconium and zircaloy-4, respectively. The effect factors on the fatigue mechanism and the thermodynamic and dynamic criteria of the dislocation-pattern evolution are discussed.

• Sponsoring Organization: National Natural Science Foundation of China, Beijing, BJ (China)
• OSTI ID: 484851
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 4 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL DEFECTS
DEFORMATION
DISLOCATIONS
FATIGUE
PLASTICITY
SLIP
STRAINS
TWINNING
ZIRCALOY 4
ZIRCONIUM