Observation of processes of superplasticity with the scanning electron microscope

Hotz, W.; Ruedl, E.; Schiller, P.

doi:10.1007/bf00754492

Cited by 30 publications

(5 citation statements)

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“…With the assumption that essentially the same deformation process operating in the sample interior is also operating on the sample surface during sample deformation, numerous studies have examined surface microstructures after deformation of polycrystalline materials including metallic [e.g., Hotz et al ., ; Vastava and Langdon , ] and ceramic materials [e.g., Langdon , ; Cannon and Sherby , ]. Most of the deformation experiments, including this study, were conducted in a uniaxial geometry and analyzed a lateral surface of the sample parallel to the deformation axis.…”

Section: Identification Of Deformation Processes At the Sample Surfacementioning

confidence: 99%

Grain‐ to multiple‐grain‐scale deformation processes during diffusion creep of forsterite + diopside aggregate: 1. Direct observations

Maruyama

Hiraga

2017

JGR Solid Earth

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We uniaxially deformed fine‐grained (~ 1 μm) forsterite + diopside (5 and 20 vol %) aggregates in the diffusion creep regime. Prior to deformation, line markers were milled on a lateral surface of a cylindrical sample to detect single‐ to multiple‐grain‐scale deformation. We performed deformation experiments and observations of the marker‐etched surface after sample cooling multiple times on the same specimens. The strain measured at the scale of several tens of grains from macroscopic shortening of the markers parallel to the compression axis is consistent with the total strain of the sample. However, microscopically, the markers are intensely segmented and rotated at the grain scale increasing with the sample strain. Meanwhile, essentially, no deformation is observed within the grains in most of the samples. The surface microstructures, including the deformation of the markers, reveal the serial operations of grain boundary migration, grain boundary sliding, rigid body grain rotation, and grain neighbor switching, which correspond well to processes expected in diffusion‐controlled superplasticity. This sequence is commonly observed in both samples consisting of forsterite grains of tabular and equiaxed grain shapes, which have been shown to develop notable crystallographic preferred orientation (CPO) and random (or weak) CPO, respectively, during diffusion creep. Intragranular regions of relatively larger forsterite grains in the specimens deformed at stresses near the transition between deformation mechanisms from diffusion creep to dislocation creep reveal marker deformation and formation of surface creases and subgrain boundaries, which indicate intragranular dislocation processes. Overall, the surface microstructures reflect the deformation state of the materials well.

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Section: Identification Of Deformation Processes At the Sample Surfacementioning

confidence: 99%

Grain‐ to multiple‐grain‐scale deformation processes during diffusion creep of forsterite + diopside aggregate: 1. Direct observations

Maruyama

Hiraga

2017

JGR Solid Earth

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“…The study of boundary sliding in Sn-Pb eutectic is not new; many studies have focused on in situ observations of the sliding behavior by SEM (Hotz et al, 1975;Geckinli and Barrett, 1976;Furushiro and Hori, 1979;Vastava and Langdon, 1979;Rai and Grant, 1983;Kashyap et al, 1985;Valiev and Langdon, 1993;Zelin et al, 1993). These observations, however, were limited to the free surface of the specimen.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent microstructure-based continuum damage models have been constructed largely following this conception (Vianco et al, 1999;Wei et al, 2001). It has long been recognized, however, that the primary deformation mechanism in Sn-Pb eutectic is grain boundary sliding (Hotz et al, 1975;Geckinli and Barrett, 1976;Furushiro and Hori, 1979;Vastava and Langdon, 1979;Rai and Grant, 1983;Kashyap et al, 1985;Valiev and Langdon, 1993;Zelin et al, 1993). Since grain boundary sliding can occur within a short time-scale without the influence of atomic diffusion, its effect on damage evolution in Sn-Pb solder needs to be explored.…”

Section: Introductionmentioning

confidence: 99%

Effects of Grain Boundary Sliding on Microstructural Evolution and Damage Accumulation in Tin-Lead Alloy

Shen

Abell

Garrett

2004

International Journal of Damage Mechanics

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Experiments on the eutectic tin-lead (Sn-Pb) alloys were conducted to study the effects of grain boundary sliding on the deformation and damage processes at the microscopic level. The primary objective is to gain mechanistic undersanding of solder joint reliability in microelectronic packaging. Bulk specimens were subjected to relatively fast deformations of tension, compression, and bending, for the purposes of examining the pure mechanical effect without the influence of diffusion-related phenomena. Grain realignment and phase redistribution were characterized by microscopy and microhardness indentation. A micromechanical model is proposed to elucidate the observed microstructural changes and progressive damage. This study illustrates the significance of damage in the form of microscopic heterogeneity caused by grain boundary sliding. It also illustrates the possibility of mechanically induced phase coarsening in actual solder joints. High-frequency cyclic shear tests on Sn-Pb solder joints showed damage along the coarsened band after only a short time, in accord with the proposed effects. Boundary sliding without the influence of atomic diffusion plays an essential role in fatigue damage in solder.

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“…The fluctuation feature of the grain rotation was suggested by the scratch mark offset records [15] and in situ surface experiments [16] concerning superplastic deformation. The perception of geometrically necessary dislocations (GND) for a polycrystalline metal [lr] may be borrowed to simulate the integrity of interlayers separating the nanograin cores.…”

Section: Kinematicsmentioning

confidence: 99%

Numerical simulation for deformation of nano-grained metals

杨卫

洪伟

2002

Acta Mech Sinica

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Electro-deposition technique is capable of producing nano-gralned bulk copper specimens that exhibit superplastic extensibility at room temperature. Metals of such small grain sizes deform by grains sliding, with little distortion occurring in the grain cores. Accommodation mechanisms such as grain boundary diffusion, sliding and grain rotation control the kinetics of the process. Actual deformation minimizes the plastic dissipation and stored strain energy for representative steps of grain neighbor switching. Numerical simulations based on these principles are discussed in this paper.

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Observation of processes of superplasticity with the scanning electron microscope

Cited by 30 publications

References 1 publication

Grain‐ to multiple‐grain‐scale deformation processes during diffusion creep of forsterite + diopside aggregate: 1. Direct observations

Grain‐ to multiple‐grain‐scale deformation processes during diffusion creep of forsterite + diopside aggregate: 1. Direct observations

Effects of Grain Boundary Sliding on Microstructural Evolution and Damage Accumulation in Tin-Lead Alloy

Numerical simulation for deformation of nano-grained metals

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