Superplastic Deformation Mechanism of ZrO2 and Al2O3 with Additives Studied by Electron Microscopy

Abstract The fracture behavior and deformation mechanism of polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) were studied by scanning electron microscopy and transmission electron microscopy analyses. The deformation mechanism was investigated under different conditions. Voids were seen under all the conditions because of matrix shear yielding, indicating that rubber particle cavitation took place during the blend fracture process; moreover, the void size and density increased as the fracture surface was approached. However, the void density and extent of elongation of the rubber particles in the deformation zone decreased with increasing test speed rate. Many voids were positioned in the rubber particles, confirming that matrix shear yielding initiated by rubber particle cavitation was the main deformation mechanism during ductile fracture in the matrix.

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A Novel Deformation Mechanism for Superplastic Deformation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.166.103 ◽

1999 ◽

Vol 166 ◽

pp. 103-108 ◽

Cited By ~ 9

Author(s):

Hachizo Muto ◽

Mototsugu Sakai

Keyword(s):

Deformation Mechanism ◽

Superplastic Deformation

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Microstructural Evolution and Deformation Mechanisms for Superplasticity of NiAl Intermetallic

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.2995 ◽

2005 ◽

Vol 475-479 ◽

pp. 2995-2998

Author(s):

Jian Ting Guo ◽

Rong Shi Chen ◽

Xing Hao Du ◽

Gu Song Li ◽

Lan Zhang Zhou

Keyword(s):

Electron Microscopy ◽

Microstructural Evolution ◽

Superplastic Deformation ◽

Tensile Elongation ◽

Deformation Mechanisms ◽

High Angle ◽

Continuous Dynamic Recrystallization ◽

Transmission Electron ◽

Continuous Dynamic ◽

Temperature Strain

The microstructural evolution during superplastic deformation of the extruded stoichiometric NiAl polycrystals were systemically investigated in various conditions of temperature, strain rate and strain by means of optical microscopy (OM) and transmission electron microscopy (TEM). Consequently, The deformation microstructures corresponding to the large tensile elongation consisted of subgrains, low angle grains as well as high angle grains, which indicated that continuous dynamic recrystallization (CDRX) process was operating during superplastic deformation.

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Time-resolved high-resolution electron microscopy of structural transformation in nanocrystalline ZnO films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167354 ◽

1996 ◽

Vol 54 ◽

pp. 978-979

Author(s):

T. Kizuka ◽

N. Tanaka

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Grain Boundary ◽

Structural Transformation ◽

Superplastic Deformation ◽

Boundary Migration ◽

High Resolution Electron Microscopy ◽

Grain Boundary Migration ◽

Time Resolved ◽

Resolution Electron

Mechanical properties of polycrystalline materials become anomalous when the grain size and grain boundary length decrease to nanometer scale. For example, ductility and toughness increase significantly in nanometer-grained ceramics (nanocrystalline ceramics). Ductility increases due to appearance of fine-grained-superplastic deformation. Grain boundary migration and interface migration are fundamental processes of the superplastic deformation. Structural transformation of fine grains is a factor which limits the toughness in polycrystalline ceramics because the transformation relaxes internal strain. The behavior of grain boundaries and interfaces, such as diffusion bonding and Czochralski-type crystal growth at ambient temperature, can be analyzed by a time-resolved high-resolution electron microscopy (TRHREM) developed by Kizuka et al.,In the present study, grain boundary migration and successive transformation of crystal structure in nanocrystalline ZnO were investigated by TRHREM.Zinc oxide was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at 200°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder.

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Microstructural Evolution of a Fine-Grained Mg-Y-Nd Alloy during Superplastic Deformation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.849.162 ◽

2016 ◽

Vol 849 ◽

pp. 162-167

Author(s):

Geng Hua Cao ◽

Da Tong Zhang

Keyword(s):

Electron Microscopy ◽

Strain Rate ◽

Superplastic Deformation ◽

Grain Boundary Sliding ◽

Second Phase ◽

Friction Stir ◽

Fine Grained ◽

Average Grain Size ◽

Temperature Ranges ◽

Increasing Temperature

Cast Mg-4.27Y-2.94Nd-0.51Zr (wt.%) alloy was subjected to submerged friction stir processing (SFSP) with at a rotation rate of 600 rpm and a traveling speed of 60 mm min-1. Superplastic behavior of specimens with an average grain size of ~1.3 μm were investigated in the temperature ranges of 683-758 K and the strain rate ranges from 1×10-1 to 4×10-4 s-1. Microstructure characteristics were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the maximum elongation of 967% was obtained at 733 K and 3×10-3 s-1, the optimal HSRS of 900% achieved at 758 K and 2×10-2 s-1. Grains and second phase particles grew coarser with the increasing temperature or decreasing strain rate. Remarkable grain growth is the main reason that elongations are all significantly decreased when the strain rate decrease from 3×10-3 s-1 to 4×10-4 s-1. Grain boundary sliding is the main mechanism during superplastic deformation.

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