The effect of excess neodymia on the grain growth of Nd1+xBa2−xCu3Oy solid solutions

The grain growth of dense, fine-grained Nd1+xBa2−xCu3Oy (x = 0.1−0.4) specimens has been examined in pure O2(g) at 938 °C and 967 °C. No detectable change in average grain size was observed for Nd1.4Ba1.6Cu3Oy within 72 h at 967 °C; however, a significant increase in average grain size developed between 18 and 24 h at 967 °C for Nd1.3Ba1.7Cu3Oy, and within 8−12 h at ≤967 °C for Nd1.2Ba1.8Cu3Oy and Nd1.1Ba1.9Cu3Oy. Microstructural analyses revealed that sudden changes in average grain size coincided with the formation of relatively large (abnormal) grains. A broadening of the grain size distribution was also observed. TEM analyses revealed that grain boundaries were free of second phases. The possible role of anisotropy in grain boundary energy and/or mobility on grain growth is discussed.

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Effect of Grain Boundary Energy in Recrystallization Simulation by Phase Field Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.953 ◽

2020 ◽

Vol 993 ◽

pp. 953-958

Author(s):

Yan Wu ◽

Ren Chuang Yan ◽

Er Wei Qin ◽

Wei Dong Chen

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Grain Growth ◽

Phase Field ◽

Boundary Energy ◽

Phase Field Model ◽

Field Method ◽

Phase Field Method ◽

Grain Boundary Energy ◽

Average Grain Size

In this paper, the effect of grain boundary energy in AZ31 Mg alloy with multi-order parameters phenomenological phase field model has been discussed during the progress of recrystallization. The average grain size of the recrystallization grain at a certain temperature and a certain restored energy but various grain boundary energies have been studied, and the simulated results show that the larger the grain boundary energy is, the larger the average grain size will be, and the speed of grain growth will increase with the increase of grain boundary energy. Additionally, temperature will also increase the grain growth rate.

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Dynamic Grain Growth in Superplastic Y-TZP and Al2O3/YTZ

MRS Proceedings ◽

10.1557/proc-196-343 ◽

1990 ◽

Vol 196 ◽

Cited By ~ 3

Author(s):

T. G. Nieh ◽

C. M. Tomasello ◽

J. Wadsworth

Keyword(s):

Growth Rate ◽

Grain Size ◽

Grain Growth ◽

Kinetic Constant ◽

Boundary Energy ◽

Tetragonal Zirconia ◽

Grain Boundary Energy ◽

Fine Grained ◽

Dynamic Grain Growth ◽

Similar Equation

ABSTRACTBoth static and dynamic grain growth have been studied during superplastic deformation of fine-grained yttria-stabilized tetragonal zirconia (Y-TZP) and alumina reinforced yttria-stabilized tetragonal zirconia (Al2O3/YTZ). Grain growth was observed in both materials at temperatures above 1350° C. In the case of Y-TZP, both static and dynamic grain growth were found to obey a similar equation of the form: where D is the instantaneous grain size, Do is the initial grain size, t is the time, and k is a kinetic constant which depends primarily on temperature and grain boundary energy. The activation energies for Y-TZP were approximately 580 and 520 kJ/mol, for static and dynamic grain growth, respectively. In the case of Al2O3/YTZ, it was found that the grain growth rate for the Al2O3 phase was slower than that for the ZrO2 phase. The growth rate of the ZrO2 phase in Al2O3/YTZ is, however, similar to that in monolithic ZrO2, i.e., Y-TZP.

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The Role of Grain Boundary Energy in Texture Controlled Grain Growth

Materials Science Forum ◽

10.4028/www.scientific.net/msf.94-96.391 ◽

1992 ◽

Vol 94-96 ◽

pp. 391-398 ◽

Cited By ~ 9

Author(s):

I. Heckelmann ◽

Giuseppe Carlo Abbruzzese ◽

K. Lücke

Keyword(s):

Grain Boundary ◽

Grain Growth ◽

Boundary Energy ◽

Grain Boundary Energy

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Dome Concordia ice microstructure: impurities effect on grain growth

Annals of Glaciology ◽

10.3189/172756402781816573 ◽

2002 ◽

Vol 35 ◽

pp. 552-558 ◽

Cited By ~ 20

Author(s):

Jérôme Weiss ◽

Jérôme Vidot ◽

Michel Gay ◽

Laurent Arnaud ◽

Paul Duval ◽

...

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Grain Boundaries ◽

Grain Growth ◽

Growth Process ◽

Boundary Energy ◽

Ice Core ◽

Dust Particles ◽

The Holocene ◽

Average Grain Size

AbstractWe present a detailed analysis of the microstructure in the shallow part (100–580m) of the European Project for Ice Coring in Antarctica (EPICA) ice core at Dome Concordia. In the Holocene ice, the average grain-size increases with depth. This is the normal grain-growth process driven by a reduction of the total grain-boundary energy. Deeper, associated with the Holocene–Last Glacial Maximum (LGM) climatic transition, a sharp decrease of the average grain-size is observed. to explain modifications to the microstructure with climatic change, we discuss the role of soluble and insoluble (microparticles) impurities in the grain-growth process of Antarctic ice, coupled with an analysis of the pinning of grain boundaries by microparticles. Our data indicate that high soluble impurity content does not necessarily imply a slowing-down of grain-growth kinetics, whereas the pinning of grain boundaries by dust particles located along the boundaries does explain modifications to the microstructure (small grain-sizes; change in grain-size distributions, etc.) observed in volcanic ash layers or dusty LGM ice.Moreover, classical mean-field models of grain-boundary pinning are in good quantitative agreement with the evolution of grain-size along the EPICA ice core. This suggests a major role for dust in the modification of shallow polar ice microstructure.

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Competition between grain growth and grain-size reduction in polar ice

Journal of Glaciology ◽

10.3189/002214311798043690 ◽

2011 ◽

Vol 57 (205) ◽

pp. 942-948 ◽

Cited By ~ 20

Author(s):

Jens Roessiger ◽

Paul D. Bons ◽

Albert Griera ◽

Mark W. Jessell ◽

Lynn Evans ◽

...

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Grain Growth ◽

Boundary Migration ◽

Boundary Energy ◽

Ice Core ◽

Size Reduction ◽

Polar Ice ◽

Average Grain Size ◽

Log Normal

AbstractStatic (or ‘normal’) grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factorkin the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factorkalso incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase inkby a factor of 3.5.

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The Relationship between Grain Boundary Energy, Grain Boundary Complexion Transitions, and Grain Size in Ca-Doped Yttria

Materials Science Forum ◽

10.4028/www.scientific.net/msf.753.87 ◽

2013 ◽

Vol 753 ◽

pp. 87-92 ◽

Cited By ~ 8

Author(s):

Stephanie A. Bojarski ◽

Jocelyn Knighting ◽

Shuai Lei Ma ◽

William Lenthe ◽

Martin P. Harmer ◽

...

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Size Distribution ◽

Grain Growth ◽

Lower Energy ◽

Boundary Energy ◽

Grain Boundary Energy ◽

Entire Sample ◽

Small Grains ◽

The Relationship

The thermal groove technique has been used to measure relative grain boundary energies in two 100 ppm Ca-doped yttria samples. The first has a normal grain size distribution and the boundaries have a bilayer of segregated Ca. In the second sample, there is a combination of large grains and small grains. The boundaries around the large grains are known to have an intergranular film. The results show that the relative energies of boundaries in the sample with normal grain growth and the boundaries around small grains far from larger grains in the second sample are similar. Also, boundaries surrounding the largest grains and small grains immediately adjacent to them have the same and significantly lower energies. The results indicate that grain boundaries with an intergranular film have a lower energy than those with bilayer segregation and that the intergranular film extends beyond the periphery of the largest grains, but not throughout the entire sample.

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