The Effect of Grain Size and SiC Particulates on the Strength and Ductility of MoSi2

1993 ◽  
Vol 322 ◽  
Author(s):  
Amit K. Ghosh ◽  
Ajoy Basu
Keyword(s):  
Grain Size ◽  
Compression Behavior ◽  
Grain Sizes ◽  
Fine Grain ◽  
Compression Creep ◽  
The Matrix ◽  
Tension And Compression ◽  
Sic Particulates ◽  
Ductile To Brittle Transition ◽  
Strength And Ductility

AbstractMonolithic MoSi2 and MoSi2 reinforced with SiC particulate reinforcements have been produced with widely varying grain sizes. Monotonic compression behavior of these materials has been examined in the temperature range of room temperature to 1200°C. Based on these results, the ductile-to-brittle transition temperature at low deformation rate of MoSi2 and its composite appears to be near 900°C and may decrease slightly with decreasing grain size. Tension and compression creep behavior of these materials were also studied between 1100 and 1400°C. Creep strength of the matrix decreases with decreasing grain size even in the nominally dislocation climb-glide regime. While 20 vol% SiC particulates provide a reasonable amount of creep strengthening of the fine grain MoSi2 matrix, strengthening due to coarser grain size can be significantly higher in these materials. These results parallel those on other intermetallics.

The Method of Eliminating Banded Structure and the Effects of Banded Structure on the Transverse Properties in 20G Steel

2013 ◽  
Vol 347-350 ◽  
pp. 1171-1175 ◽  
Author(s):  
Bin Wang ◽  
Hong Mei Hu ◽  
Cui Zhou
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Stress Concentration ◽  
Base Metal ◽  
Metallic Inclusion ◽  
Banded Structure ◽  
Grain Sizes ◽  
Fine Grain ◽  
Treatment Processes ◽  
Metallic Inclusions

The transverse properties were inferior to the longitudinal properties for the existence of banded structure in 20G steel. In order to eliminate the banded structure and improve the transverse performance of 20G steel, different heat treatment processes were adopted. The results showed that conventional normalizing could reduce the banded structure and refine the grain sizes. When 20G was heated with 10°C/min heating rated and then held at 920°C for 2h, the banded structure in the steel was almost eliminated and the microstructure was homogeneous with fine grain size, the strength increased by 14%. The non-metallic inclusion and carbide in the microstructure leaded to stress concentration and separation with the base metal. To some extent, heat treatment can improve the distribution and form of non-metallic inclusions.

scholarly journals Influence of the Matrix Grain Size on the Apparent Density and Bending Strength of Sand Cores

2017 ◽  
Vol 17 (1) ◽  
pp. 27-30
Author(s):  
R. Dańko
Keyword(s):  
Grain Size ◽  
Apparent Density ◽  
Bending Strength ◽  
Diffraction Method ◽  
Laser Diffraction ◽  
Grain Sizes ◽  
The Matrix

Abstract The results of investigations of the influence of the matrix grain sizes on properties of cores made by the blowing method are presented in the hereby paper. Five kinds of matrices, differing in grain size compositions, determined by the laser diffraction method in the Analysette 22NanoTec device, were applied in investigations. Individual kinds of matrices were used for making core sands in the Cordis technology. From these sands the shaped elements, for determining the apparent density of compacted sands and their bending strength, were made by the blowing method. The shaped elements (cores) were made at shooting pressures being 3, 4 and 5 atn. The bending strength of samples were determined directly after their preparation and after the storing time of 1 hour.

scholarly journals Effect of Grain Size on Carburization Characteristics of the High-Entropy Equiatomic CoCrFeMnNi Alloy

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7199
Author(s):  
Hyunbin Nam ◽  
Jeongwon Kim ◽  
Namkyu Kim ◽  
Sangwoo Song ◽  
Youngsang Na ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Grain Sizes ◽  
Fine Grain ◽  
Cast Specimen ◽  
Vacuum Carburization ◽  
Cold Rolled ◽  
Face Centered

In this study, the carburization characteristics of cast and cold-rolled CoCrFeMnNi high-entropy alloys (HEAs) with various grain sizes were investigated. All specimens were prepared by vacuum carburization at 940 °C for 8 h. The carburized/diffused layer was mainly composed of face-centered cubic structures and Cr7C3 carbide precipitates. The carburized/diffused layer of the cold-rolled specimen with a fine grain size (~1 μm) was thicker (~400 μm) than that of the carburized cast specimen (~200 μm) with a coarse grain size (~1.1 mm). In all specimens, the carbides were formed primarily through grain boundaries, and their distribution varied with the grain sizes of the specimens. However, the carbide precipitates of the cast specimen were formed primarily at the grain boundaries and were unequally distributed in the specific grains. Owing to the non-uniform formation of carbides in the carburized cast specimen, the areas in the diffused layer exhibited various carbide densities and hardness distributions. Therefore, to improve the carburization efficiency of equiatomic CoCrFeMnNi HEAs, it is necessary to refine the grain sizes.

Improvement of Strength and Ductility by Combining Static Recrystallization and Unique Heat Treatment in Co-20Cr-15W-10Ni Alloy for Stent Application

2021 ◽  
Vol 1016 ◽  
pp. 1503-1509
Author(s):  
Kosuke Ueki ◽  
Soh Yanagihara ◽  
Kyosuke Ueda ◽  
Masaaki Nakai ◽  
Takayoshi Nakano ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Static Recrystallization ◽  
High Strength ◽  
Small Variation ◽  
Grain Structure ◽  
Fine Grain ◽  
High Temperature Short Time ◽  
Average Grain Size ◽  
Strength And Ductility

The Co-20Cr-15W-10Ni (CCWN, mass%) alloy has excellent corrosion resistance and strength-ductility balance and is applied in almost all balloon-expandable stent platforms. To further reduce the invasiveness of stent placement, it is necessary to reduce the diameter of the stent. That is, both high strength and high ductility should be achieved while maintaining a low yield stress. In our previous studies, it was discovered that low-temperature heat-treatment (LTHT) at 873 K improves the elongation of the CCWN alloy. In this study, we focused on the grain refinement by swaging and static recrystallization to improve the strength of the alloy. The as-swaged alloy was recrystallized at 1373–1473 K for 100–300 s, followed by LTHT. A fine grain structure with an average grain size of 3–17 μm was obtained by static recrystallization. The η-phase (M12X-M6X type precipitates, M: metallic elements, X: C and/or N) formed during the recrystallization at 1373–1448 K. The alloys recrystallized at 1448 and 1473 K had a homogeneous structure with a small variation in the grain size. On the other hand, the alloys recrystallized at 1373 and 1423 K had an inhomogeneous structure in which fine and coarse grains were mixed. Both the strength and ductility of the CCWN alloy were improved by combining high-temperature short-time recrystallization and LTHT.

Jadeite–K-feldspar rocks and jadeitites from northwest Turkey

1997 ◽  
Vol 61 (409) ◽  
pp. 835-843 ◽  
Author(s):  
Aral I. Okay
Keyword(s):  
Grain Size ◽  
Debris Flows ◽  
Bulk Rock ◽  
Rock Composition ◽  
Bulk Rock Composition ◽  
Fine Grained ◽  
Fine Grain ◽  
The Matrix ◽  
Mineral Pair

AbstractBlueschist-facies rocks with jadeite-K-feldspar-lawsonite paragenesis occur as exotic blocks in Miocene debris flows in the blueschist belt of northwest Turkey. The jadeite-K-feldspar rocks have a very fine grain size and although recrystallized locally retain a relict porphyritic volcanic texture. The former nepheline microphenocrysts, recognized from their characteristic shapes, are pseudomorphed by jadeite and K-feldspar, while the relict magmatic aegirine has rims of jadeite. The matrix of the rock consists of very fine-grained aggregates of jadeite, K-feldspar and lawsonite. In some blocks, jadeite makes up >60% of the mode. Jadeite, K-feldspar and lawsonite in the blocks are essentially pure end-member in composition. P-T estimates for these rocks are 8 ± 2 kbar and 300 ± 50°C. The preserved volcanic texture, relict aegirine and the bulk rock composition indicate that these rocks represent metamorphosed phonolites. The paragenesis in these rocks shows that jadeite-K-feldspar is a stable mineral pair in blueschist-facies P-T conditions.

Effect of Grain Size on the Isothermal Oxidation of Fe-33Ni-19Cr Alloys at 700 °C

2013 ◽  
Vol 845 ◽  
pp. 56-60
Author(s):  
Noraziana Parimin ◽  
Esah Hamzah ◽  
Astuty Amrin
Keyword(s):  
Grain Size ◽  
Oxidation Behavior ◽  
Annealing Treatment ◽  
Isothermal Oxidation ◽  
Coarse Grain ◽  
X Ray ◽  
Fine Grain ◽  
The Matrix ◽  
Different Temperatures ◽  
Different Grain Size

The isothermal oxidation behavior of two different grain size of Fe-33Ni-19Cr alloys was investigated at 700 °C in laboratory air. Different grain size of alloyed was made of solution annealing treatment at different temperatures, namely, 1050 °C and 1150 °C for fine and coarse grain, respectively. Optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were employed in this study to analyze the oxidation behavior of solution-annealed samples. Results indicate that the fine grain size solution-annealed alloys possess a better oxidation resistance and reduced oxidation rate than the coarse grain. The differences observed are attributed to the finer grains increasing the relaxation of the oxide scale stress and improving the adhesion of the oxide layer on the matrix.

Microstructure and Mechanical Properties of Quasicrystal Reinforced Magnesium Matrix Composites

2011 ◽  
Vol 686 ◽  
pp. 242-246
Author(s):  
Xu Dong Wang ◽  
Wen Bo Du ◽  
Chao Hui Wang ◽  
Shu Bo Li
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Maximum Yield ◽  
Icosahedral Quasicrystal ◽  
Strengthening Effect ◽  
Magnesium Matrix Composites ◽  
Fine Grain ◽  
Average Grain Size ◽  
The Matrix ◽  
Maximum Yield Strength

Magnesium-based composites reinforced with stable icosahedral quasicrystal particles have been fabricated via Repeated Plastic Working (RPW) process. The microstructure of the composites has been investigated by XRD, SEM, TEM and HREM, and its mechanical properties have also been studied. The results showed that the RPW process could reduce the matrix grain size significantly, and the average grain size of matrix was only about 500 nm after 200 cycles of RPW. A good metallurgical bond interface between the quasicrystal particles and the Mg matrix was found. The composites exhibited the maximum yield strength of 265MPa and the maximum ultimate tensile strength of 309MPa at room temperature, respectively. The enhancement of mechanical properties is attributed to the strengthening effect of the quasicrystal particles and the fine-grain size of matrix.

1200 to 1400 K slow strain rate compressive behavior of small grain size NiAl/Ni2AlTi alloys and NiAl/Ni2AlTi–TiB2 composites

1989 ◽  
Vol 4 (5) ◽  
pp. 1164-1171 ◽  
Author(s):  
J. Daniel Whittenberger ◽  
R. K. Viswanadham ◽  
S. K. Mannan ◽  
K. S. Kumar
Keyword(s):  
Grain Size ◽  
Elevated Temperature ◽  
Matrix Material ◽  
Matrix Composition ◽  
Strain Rates ◽  
Transverse Cracks ◽  
State Behavior ◽  
Strain Behavior ◽  
Grain Sizes ◽  
The Matrix

Since 1976 NiAl–Ni2AlTi alloys have been known to possess elevated temperature mechanical properties approaching those of Ni-base superalloys; however, due to their apparent brittleness, little additional work has been undertaken to exploit this strength. In an attempt to instill ductility in these materials, small grain size single (Ni–45Al–5Ti) and two (Ni–40Al–10Ti) phase intermetallics were fabricated by XDTM technology and tested (XDTM is a trademark of Martin Marietta Corporation). As these compositions have the potential for being the matrix material in high temperature composites, Ni–40Al–10Ti and Ni–45Al–5Ti with 20 vol.% TiB2 in the form of ∼1 μm diameter particles were also investigated. The as-fabricated materials were fully dense and polycrystalline. The grain sizes measured ∼8 μm for Ti-poor and about 15 μm for the Ti-rich unreinforced materials but could not be determined for either TiB2 containing composite. Elevated temperature compression testing was conducted to about 8% deformation between 1200 and 1400 K with strain rates varying from ∼10−4 to ∼10−7 s−1. The majority of the tests exhibited diffuse yielding over approximately 1% strain followed by negative strain hardening. However, a few experiments resulted in steady state behavior where deformation continued under a constant stress. The flow strengths on yielding of both forms of Ni–40Al–10Ti were higher than those for the Ni–45Al–5Ti versions. For each matrix composition the addition of 20 vol.% TiB2 decreased the strength at the higher strain rates in comparison to the TiB2-free forms. During slow deformation conditions, however, the particles do provide reinforcement. Light optical microscopy of tested specimens revealed that these materials are generally quite brittle as numerous longitudinal and transverse cracks were found irrespective of the type of stress-strain behavior.

Fine Grained AZ31 by Conventional Thermo-Mechanical Processing

2009 ◽  
Vol 618-619 ◽  
pp. 239-244
Author(s):  
Nicole Stanford
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Fine Grained ◽  
Specific Strength ◽  
Magnesium Alloy Az31 ◽  
Grain Sizes ◽  
Processed Material ◽  
Property Space ◽  
Rolled Condition ◽  
Strength And Ductility

The magnesium alloy AZ31 was processed by severe hot rolling and annealing. This processing was optimised to produce recrystallised grain sizes as small as 2.2μm. Specimens in the as-rolled condition had a grain size of 0.5μm, and exhibited a yield strength in excess of 350MPa. In the fully recrystallised condition, with a grain size of 2.2μm, the material had a yield strength of 260MPa which is almost twice that of the as-received plate. The ductility of the annealed specimens was also increased compared to the as-received condition. The combination of specific strength and ductility brings this newly processed material into a new property space compared to the other light metals.

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