Grain boundary migration in high-temperature deformation

Uniaxial compression deformation is conducted on solid solution Al-3mass%Mg and Al-3mass%Mg-0.2mass%Sc with Al3Sc precipitates in the strain rates ranging from 1.0×10-4s-1 to 5.0×10-3s-1 at 723K. High temperature yielding is observed. Fiber texture is constructed in all the deformation conditions. While the main component of the fiber texture changes from {011} to {001} in Al-3mass%Mg alloy with an increase in strain rate, no big change in texture main component is seen for Al-3mass%Mg-0.2mass%Sc alloy with Al3Sc precipitates. It is experimentally shown that the development of {001} fiber texture can be attributed to the grain boundary migration.

Download Full-text

Development of microstructure in the high-temperature deformation of ice

Annals of Glaciology ◽

10.1017/s0260305500013562 ◽

1996 ◽

Vol 23 ◽

pp. 293-302 ◽

Cited By ~ 6

Author(s):

Christopher J. L. Wilson ◽

Yanhua Zhang

Keyword(s):

Grain Boundary ◽

Boundary Migration ◽

Time Lapse ◽

Grain Structure ◽

High Temperature Deformation ◽

Temperature Deformation ◽

Grain Boundary Migration ◽

Crystallographic Slip ◽

Polycrystalline Ice ◽

Time Lapse Photography

Microstructural changes in three sets of experiments involving crystallographic slip in anisotropic polycrystalline ice are described and interpreted with the aid of computer models. The development of microstructure was followed using time-lapse photography and transmitted light observations with deformation undertaken in plane strain and at a temperature of approximately –1°C. The deformation within a grain aggregate that accompanies axial shortening is always heterogeneous on a grainscale. The extent of inhomogeneity varies depending on the pre-existing grain structure and the way it can accommodate intragranular slip. Grain interactions are extremely important in determining the bulk deformation and the degree of grain-boundary migration. A consequence of shortening of the aggregate is the formation of high stresses between neighbouring grains and under the appropriate conditions there may be either grain-boundary migration or melting at these sites. Where a sample undergoes translation and shear during deformation, anisotropic grains in the appropriate orientation undergo bending. A buckle instability may then develop and much of the strain is accommodated by grains in easy-glide orientations. In such situations, the ice undergoes extensive recrystallization and grain growth that is concentrated in the areas of greatest buckling.

Download Full-text

Development of microstructure in the high-temperature deformation of ice

Annals of Glaciology ◽

10.3189/s0260305500013562 ◽

1996 ◽

Vol 23 ◽

pp. 293-302 ◽

Cited By ~ 6

Author(s):

Christopher J. L. Wilson ◽

Yanhua Zhang

Keyword(s):

Grain Boundary ◽

Boundary Migration ◽

Time Lapse ◽

Grain Structure ◽

High Temperature Deformation ◽

Temperature Deformation ◽

Grain Boundary Migration ◽

Crystallographic Slip ◽

Polycrystalline Ice ◽

Time Lapse Photography

Microstructural changes in three sets of experiments involving crystallographic slip in anisotropic polycrystalline ice are described and interpreted with the aid of computer models. The development of microstructure was followed using time-lapse photography and transmitted light observations with deformation undertaken in plane strain and at a temperature of approximately –1°C. The deformation within a grain aggregate that accompanies axial shortening is always heterogeneous on a grainscale. The extent of inhomogeneity varies depending on the pre-existing grain structure and the way it can accommodate intragranular slip. Grain interactions are extremely important in determining the bulk deformation and the degree of grain-boundary migration. A consequence of shortening of the aggregate is the formation of high stresses between neighbouring grains and under the appropriate conditions there may be either grain-boundary migration or melting at these sites. Where a sample undergoes translation and shear during deformation, anisotropic grains in the appropriate orientation undergo bending. A buckle instability may then develop and much of the strain is accommodated by grains in easy-glide orientations. In such situations, the ice undergoes extensive recrystallization and grain growth that is concentrated in the areas of greatest buckling.

Download Full-text

Increased Thermal Stability of Co-silicide Using Co-Ta Alloy Films

MRS Proceedings ◽

10.1557/proc-670-k6.5 ◽

2001 ◽

Vol 670 ◽

Author(s):

Min-Joo Kim ◽

Hyo-Jick Choi ◽

Dae-Hong Ko ◽

Ja-Hum Ku ◽

Siyoung Choi ◽

...

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Grain Boundary ◽

Reaction Rate ◽

Boundary Migration ◽

Grain Boundary Migration ◽

Alloy Films ◽

Post Annealing ◽

Alloy Process ◽

Thermal Stability Of

ABSTRACTThe silicidation reactions and thermal stability of Co silicide formed from Co-Ta/Si systems have been investigated. In case of Co-Ta alloy process, the formation of low resistive CoSi2phase is delayed to about 660°C, as compared to conventional Co/Si system. Moreover, the presence of Ta in Co-Ta alloy films reduces the silicidation reaction rate, resulting in the strong preferential orientation in CoSi2 films. Upon high temperature post annealing in the furnace, the sheet resistance of Co-silicide formed from Co/Si systems increases significantly, while that of Co-Ta/Si systems maintains low. This is due to the formation of TaSi2 at the grain boundaries and surface of Co-silicide films, which prevents the grain boundary migration thereby slowing the agglomeration. Therefore, from our research, increased thermal stability of Co-silicide films was successfully obtained from Co-Ta alloy process.

Download Full-text