Room Temperature Strength and Fracture of FeAl And NiAl.

1990 ◽  
Vol 213 ◽  
Author(s):  
P. Nagpal ◽  
I. Baker ◽  
F. Liu ◽  
P.R. Munroe
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Stoichiometric Composition ◽  
Aluminum Concentration ◽  
Fracture Modes ◽  
Tension Tests ◽  
Lattice Resistance ◽  
Stoichiometric Alloy ◽  
Room Temperature Strength

ABSTRACTThe yield strengths (σy) of FeA1 and NiAl of various aluminum concentrations were measured as a function of grain size, d, and the results fitted to σy =σo+ kd−1/2. It was found that for NiAl the lattice resistance (σo) and Hall-Petch slope (k) have minima at the stoichiometric composition and increase with decreasing aluminum concentration, whereas for FeAl these parameters have maxima at the stoichiometric composition and decrease off this composition. In tension tests, iron-rich FeAl was shown to be ductile whereas the stoichiometric alloy is brittle. In contrast, stoichiometric NiAl shows ductility but off-stoichiometric compositions are brittle. The fracture modes of the FeAl and NiAl are predominantly intergranular at the stoichiometric compositions and become increasingly transgranular with decreasing aluminum concentration.

Room temperature strength of β-sialon (z=0.5) fabricated using fine grain size alumina powder

2001 ◽  
Vol 21 (9) ◽  
pp. 1269-1272 ◽  
Author(s):  
Kazushi Kishi ◽  
Seiki Umebayashi ◽  
Eiji Tani ◽  
Kazuhisa Shobu ◽  
Yanping Zhou
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Alumina Powder ◽  
Fine Grain ◽  
Room Temperature Strength

Thermal Shock Behavior of Nd-Doped α-Sialon Ceramics

2010 ◽  
Vol 434-435 ◽  
pp. 130-133 ◽  
Author(s):  
Chun Feng Liu ◽  
Feng Ye ◽  
Yu Zhou ◽  
Yu Dong Huang ◽  
Jian Min Zhou
Keyword(s):  
Thermal Shock ◽  
Residual Strength ◽  
Room Temperature ◽  
Stoichiometric Composition ◽  
Surface Oxidation ◽  
Cycle Times ◽  
Time Cycle ◽  
Thermal Shock Behavior ◽  
Hot Press Sintering ◽  
Room Temperature Strength

Nd--sialons with the stoichiometric composition of Nd0.333Si10Al¬2ON15 were obtained by hot-press sintering at 1800°C for 1h. The thermal shock behavior of the Nd--sialons was examined by a water-quenching technique. The influence of the thermal shock temperature difference (T) and cycle times on the residual strength was evaluated. Equiaxed -sialon grains formed together with a small amount of intergranular phase M (Nd2Si3-xAl¬xO3+xN4-x) and -sialon phase. The residual strength after a thermal shock tended to decrease gradually with increasing T above 500°C. However, the specimens exhibited an improved residual strength (~94% of the room temperature strength) after a thermal shock of T=1100°C. The residual strength presented a gradual decrease with increasing the thermal shock cycle times at T=1100°C, and was still remained ~55% of the room temperature strength after 11-time cycle. It is contributed to the surface oxidation which may results in the healing of surface cracks and the generation of surface compressive stresses.

scholarly journals Pinning Effect of In-Situ TiCp and TiBw on the Grain Size and Room Temperature Strength of (TiC + TiB)/Ti Composites

2015 ◽  
Vol 32 (0) ◽  
pp. 264-269 ◽  
Author(s):  
Lei Jia ◽  
Biao Chen ◽  
Shu-feng Li ◽  
Hisashi Imai ◽  
Katsuyoshi Kondoh
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Pinning Effect ◽  
In Situ Tic ◽  
Room Temperature Strength

scholarly journals Strain-rate sensitivity of hardness of nanocrystalline Ni75at.%Al25at.% alloy film

2003 ◽  
Vol 18 (2) ◽  
pp. 382-386 ◽  
Author(s):  
A.H.W. Ngan ◽  
J.B. Pethica ◽  
H.P. Ng
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Alloy Film ◽  
Alloy Films ◽  
Grain Sizes ◽  
Room Temperature Strength

Room-temperature indentation experiments carried out on nanocrystalline Ni75at.%Al25at.% alloy films with a range of grain sizes revealed that the strain-rate sensitivity of hardness is nearly zero and that the hardness increases as grain size decreases. The strain-rate insensitivity of hardness indicates that the room-temperature strength of these alloy films is dominated by an athermal, strain-rate-insensitive component. The hardness of the films was found to be in the range of 2.4 to 3.3 GPa, depending on grain size.

Mechanical Properties of Ultrafine Grained Two-Phase Titanium Alloy Produced by “abc” Deformation

2012 ◽  
Vol 706-709 ◽  
pp. 1859-1863 ◽  
Author(s):  
Sergey V. Zherebtsov ◽  
Sergey Kostjuchenko ◽  
Egor A. Kudryavtsev ◽  
Svetlana Malysheva ◽  
Maria A. Murzinova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Titanium Alloy ◽  
Impact Toughness ◽  
Room Temperature ◽  
Tensile Elongation ◽  
Two Phase ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure ◽  
Room Temperature Strength

The mechanical properties of two-phase Ti-6Al-4V titanium alloy with ultrafine grained microstructure were studied in the present work. Bulk ultrafine grained specimens of the alloy were produced by means of warm “abc” deformation. The final structure consisted of α/β particles with a size of 500 nm. Extensive studies of the mechanical properties of this material in comparison with conventionally heat-strengthened condition were conducted. A room-temperature strength and fatigue resistance of the ultrafine grained material was found to be 25-40% higher than that of heat-strengthened alloy. However such ductility related properties as tensile elongation and impact toughness noticeably decreased with decreasing grain size. Efficacy of ductility improvement and the strength/ductility balance optimization were analyzed.

Peritectic Reaction of High Nb and W Pentatomic TiAl-Based Alloy

2011 ◽  
Vol 335-336 ◽  
pp. 831-835
Author(s):  
Hong Liang Sun ◽  
Cai Sun ◽  
Ze Wen Huang ◽  
De Gui Zhu
Keyword(s):  
Grain Size ◽  
Peritectic Reaction ◽  
Room Temperature ◽  
Aluminum Content ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Temperature Strength ◽  
Stress Rupture Life ◽  
Correlation Relationship ◽  
Room Temperature Strength

The effect of different aluminum content on peritectic reaction and mechanical properties of pentatomic TiAl-based alloy was investigated. The results indicate that the grain size gradually increase with increasing content of aluminum and addition 45.7% aluminum in TiAl-based alloy results in that the peritectic reaction can increase grain size greatly, respectively. The content of aluminum can increase the room temperature strength, high temperature strength but peritectic reaction can effectively reduce tensile strength. Aluminum content has a little effect on the ductility. The stress rupture life has positive correlation relationship with the content of aluminum.

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

2019 ◽  
Vol 12 (03) ◽  
pp. 1950032 ◽  
Author(s):  
Yuchen Deng ◽  
Yaming Zhang ◽  
Nanlong Zhang ◽  
Qiang Zhi ◽  
Bo Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Grain Size ◽  
Phase Composition ◽  
Room Temperature ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Growth Substrate ◽  
Sic Ceramics ◽  
Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

scholarly journals Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 607
Author(s):  
A. I. Alateyah ◽  
Mohamed M. Z. Ahmed ◽  
Yasser Zedan ◽  
H. Abd El-Hafez ◽  
Majed O. Alawad ◽  
...  
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Cross Section ◽  
Room Temperature ◽  
Pure Copper ◽  
High Density ◽  
Ecap Processing ◽  
Heterogeneous Distribution ◽  
Angular Pressing ◽  
Average Grain Size

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

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