An Investigation of the Structure and High Temperature Mechanical Properties of Oxide Dispersion Strengthened Alloys.

1984 ◽  
Author(s):  
W. D. Nix
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
High Temperature Mechanical Properties

Mechanical Properties of Discontinuous SiC Reinforced Aluminum Composites at Elevated Temperatures

1988 ◽  
Vol 110 (2) ◽  
pp. 77-82 ◽  
Author(s):  
T. G. Nieh ◽  
K. Xia ◽  
T. G. Langdon
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Aluminum Matrix ◽  
Oxide Dispersion Strengthened ◽  
Dislocation Motion ◽  
Particulate Composites ◽  
Oxide Dispersion ◽  
Aluminum Composites ◽  
High Temperature Mechanical Properties

High temperature mechanical properties of discontinuous, whisker and particulate, SiC reinforced aluminum composites, including 2124 and 6061 alloy matrices, are reviewed. It is shown that the behavior of these composites is similar to conventional oxide dispersion strengthened alloys. Namely, they exhibit a low strain rate senstivity and a high apparent activation energy for creep deformation. Despite the fact that the addition of SiC significantly improves the mechanical properties of aluminum at room temperature, the mechanical strength of the composite at elevated temperatures is dominated by the strength of the aluminum matrix This is because the SiC dispersoids are, in general, too coarse and they are not effective barriers for dislocation motion. It is also demonstrated that SiC particulate composites are less creep resistant than SiC whisker composites.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

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