Effect of oxidation on the mechanical properties of a NbAl3 alloy at intermediate temperatures

1992 ◽  
Vol 7 (12) ◽  
pp. 3219-3234 ◽  
Author(s):  
S.V. Raj ◽  
M. Hebsur ◽  
I.E. Locci ◽  
J. Doychak
Keyword(s):  
Mechanical Properties ◽  
Incubation Period ◽  
Surface Condition ◽  
Constant Load ◽  
Compression Tests ◽  
Cross Sectional ◽  
The Matrix ◽  
Oxide Spalling ◽  
Load Tests ◽  
Microstructural Examination

Although a NbAl3 alloy containing Cr, W, and Y has excellent oxidation resistance above 1440 K, it suffers from severe environmental attack during deformation at intermediate temperatures between 900 and 1100 K. Specimens tested in constant velocity and constant load direct compression tests showed varying degrees of degradation depending on environment (i.e., air or argon), surface finish, stress, and temperature. As a result, there were corresponding differences in mechanical behavior and in the observed microstructures. At high stresses and strain rates, specimens with as-machined surfaces were brittle at and below 1100 K when tested in air but showed fracture strains above 4% when deformed in argon. However, reproducible compressive ductility of 2–3% was attained on polished specimens tested in air. At intermediate stresses, the creep curves showed sudden and periodic increases in strain before the specimens failed catastrophically after about 80 h. Microstructural examination of these specimens revealed extensive oxidation within cracks. Constant load tests conducted at lower stresses below 100 MPa showed an apparent incubation period where the change in the length of the specimen was immeasurably small. Following the incubation period, which typically lasted between 10 and 110 h depending on stress, temperature, and surface condition, specimens increased significantly in length due to oxide growth. In this case, considerable oxide spalling occurred during the course of the test, often leading to a substantial decrease in the cross-sectional area of the specimen. Microstructural observations revealed extensive cracking in the oxide layer and in the matrix, where the cracks had originated at the oxide-metal interface. The effects of environment on the mechanical properties are rationalized with the help of a schematic environmental-deformation mechanism map.

Fabrication and Mechanical Properties of Dense/Porous β-Tricalcium Phosphate Bioceramics

2007 ◽  
Vol 330-332 ◽  
pp. 907-910
Author(s):  
Fa Ming Zhang ◽  
Jiang Chang ◽  
Jian Xi Lu ◽  
Kai Li Lin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Exponential Growth ◽  
Weight Bearing ◽  
Area Ratio ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Matrix ◽  
Porous Bioceramics

Attempt to increase the mechanical properties of porous bioceramics, a dense/porous structured β-TCP bioceramics that mimic the characteristics of nature bone were fabricated. Experimental results show that the dense/porous structured β-TCP bioceramics demonstrated excellent mechanical properties with compressive strength up to 74 MPa and elastic modulus up to 960 MPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of exponential growth. The interface between the dense and porous bioceramics is connected compactly and tightly with some micropores distributed in the matrix of both porous and dense counterparts. The dense/porous structure of β-TCP bioceramics may provide an effective way to increase the mechanical properties of porous bioceramics for bone regeneration at weight bearing sites.

scholarly journals Impact of the reinforced metal structure on the mechanical properties foamed aluminium composites at the load

2021 ◽  
Vol 8 (1) ◽  
pp. 318-326
Author(s):  
Olga Mareeva ◽  
Vladimir Ermilov ◽  
Vera Snezhko ◽  
Dmitrii Benin ◽  
Alexander Bakshtanin
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Matrix Material ◽  
Metal Structure ◽  
Absorption Capacity ◽  
Large Contribution ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Plateau ◽  
The Matrix

Abstract This paper is an experimental study of the quasi-static mechanical compressive properties of the reinforced closed-cell aluminum alloy foams with different cell orientations at different strain rates. The reinforced foam samples were obtained via the powder metallurgical route. The results of the compression tests revealed that the deformation behavior and mechanical properties of foamed aluminum composites are highly dependent on the orientation of the reinforcing mesh. Differences in the deformation behavior of foams appear to be influenced by the mechanical properties of the matrix material, by foam deformation mechanisms, and by the mechanical properties of the reinforcement. The yield stress, plateau stress, densification stress, and energy absorption capacity of unreinforced foam samples improved linearly with increasing strain rate due to dynamic recrystallization and softening of the foam matrix material. The reinforced foam samples exhibit nonlinear deformation behavior. It was also found that the mechanical properties reduction of transverse reinforced foams was slightly lower compared to foams with longitudinal reinforcement at varying strain rates because of the large contribution of the mechanical properties of the reinforcement. The results of the present study can be employed to modelling and obtain impact-resistant fillers for complex structures in transport construction.

Mechanical properties of GaAs crystals

1987 ◽  
Vol 2 (2) ◽  
pp. 252-261 ◽  
Author(s):  
Ichiro Yonenaga ◽  
Utako Onose ◽  
Koji Sumino
Keyword(s):  
Mechanical Properties ◽  
Surface Condition ◽  
Gaas Crystal ◽  
Compression Tests ◽  
Czochralski Technique ◽  
Lower Yield ◽  
Temperature Range ◽  
Defect Complexes ◽  
Transmission Electron ◽  
Effective Generation

Mechanical properties of GaAs crystals grown by the liquid encapsulated Czochralski technique and the boat technique are investigated by means of compression tests. Stressstrain characteristics of a GaAs crystal in the temperature range 400°–500°C are very similar to those of a Si crystal in the temperature range 800°–900°C. This seems to reflect the fact that the dislocation mobility in a GaAs crystal in the former temperature range is comparable to that in a Si crystal in the latter temperature range. Dislocations in GaAs crystals are found to be easily immobilized at an intermediate temperature due to gettering of impurities and/or impurity-point defect complexes. In comparison to a Si crystal, the surface of a GaAs crystal seems to involve irregularities that act easily as effective generation centers for dislocations. Thus the magnitude of the yield stress of an aged GaAs crystal is controlled by the surface condition and is not influenced by the density of dislocations involved in the crystal. The socalled steady state of deformation is realized in a GaAs crystal in the deformation stage after the lower yield point as in Si and Ge crystals. Dislocation distributions in a deformed GaAs crystal observed by transmission electron microscopy is very similar to those in deformed Si and Ge crystals.

scholarly journals The Role of Orientation and Temperature on the Mechanical Properties of a 20 Years Old Wind Turbine Blade GFR Composite

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1144
Author(s):  
Mohamed M. Z. Ahmed ◽  
Bandar Alzahrani ◽  
Nabil Jouini ◽  
Mahmoud M. Hessien ◽  
Sabbah Ataya
Keyword(s):  
Mechanical Properties ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Transverse Direction ◽  
Weight Fraction ◽  
Wind Turbine Blade ◽  
Compression Tests ◽  
Blade Length ◽  
The Matrix ◽  
Length Direction

This work evaluates the mechanical properties of the glass fiber reinforced polymer (GFRP) material taken from an out of service 100 KW power wind turbine blade which has been in service life of 20 years old. Investigated samples were taken from two positions of undamaged regions at 1.6 m and 5.4 m from the rotor hub, respectively. Microstructure investigation and lay-up analysis were carried out. Fiber weight fraction of the investigated samples was ranging between 0.55–0.60. Tensile and compression tests were carried out at the temperature range from −10 °C to +50 °C on specimens which were machined so as to be loaded in the blade length direction LD, transverse to the blade length TD and off axis; 45° to the blade length. Tensile elastic modulus of the investigated GFRP was determined in the three direction tested. The number of fiber fabric layers found to be decreasing along the blade length away from the root and the density of the fibers along the length is the highest (858 gm/mm2) and in the transverse direction is the lowest (83 gm/mm2). The microstructure of the GFRP composite showed good wetting for the fiber by the polymer with some features of lack of penetration at the high density fiber bundles and some production porosity in the matrix. The tensile Properties at room temperature (RT) and high temperature are almost similar with the highest properties for the samples aligned with the blade length. The compressive strength is highest at the transverse direction samples and lowest at the blade length direction and decreasing with the increase of the test temperature. The bending properties are significantly affected by the fiber orientation with the highest properties for samples aligned with the blade length and the lowest for the samples with the transverse direction.

scholarly journals Influence of the Cross–Sectional Shape and Corner Radius on the Compressive Behaviour of Concrete Columns Confined by FRP and Stirrups

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 341
Author(s):  
Yang Wei ◽  
Yang Xu ◽  
Gaofei Wang ◽  
Xunyu Cheng ◽  
Guofen Li
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Compression Tests ◽  
Cross Sectional ◽  
Compressive Behaviour ◽  
Corner Radius ◽  
The Cross ◽  
Sectional Shape

Axial compression tests were carried out on 72 FRP (fiber reinforced polymer)–stirrup composite−confined concrete columns. Stirrups ensure the residual bearing capacity and ductility after the FRP fractures. To reduce the effect of stress concentration at the corners of the confined square−section concrete columns and improve the restraint effect, an FRP–stirrup composite−confined concrete structure with rounded corners is proposed. Different corner radii of the stirrup and outer FRP were designed, and the corner radius of the stirrup was adjusted accurately to meet the designed corner radius of the outer FRP. The cross−section of the specimens gradually changed from square to circular as the corner radius increased. The influence of the cross−sectional shape and corner radius on the compressive behaviour of FRP–stirrup composite−confined concrete was analysed. An increase in the corner radius can cause the strain distribution of the FRP to be more uniform and strengthen the restraint effect. The larger the corner radius of the specimen, the better the improvement of mechanical properties. The strength of the circular section specimen was greatly improved. In addition, the test parameters also included the FRP layers, FRP types and stirrup spacing. With the same corner radius, increasing the number of FRP layers or densifying the stirrup spacing effectively improved the mechanical properties of the specimens. Finally, a database of FRP–stirrup composite−confined concrete column test results with different corner radii was established. The general calculation models were proposed, respectively, for the peak points, ultimate points and stress–strain models that are applicable to FRP−, stirrup− and FRP–stirrup−confined concrete columns with different cross−sectional shapes under axial compression.

Research on Processing Technology Product Design and the Application of Nano-Wood-Plastic Composite Materials

2020 ◽  
Vol 20 (12) ◽  
pp. 7787-7792
Author(s):  
Xin Fang ◽  
Jinjin Rong ◽  
Yilin Deng ◽  
Moon-Hwan Jee
Keyword(s):  
Mechanical Properties ◽  
Wood Plastic Composite ◽  
Twin Screw Extrusion ◽  
Cross Sectional ◽  
Plastic Composite ◽  
Screw Extrusion ◽  
Different Types ◽  
The Matrix ◽  
Twin Screw ◽  
Treatment Agent

This study focused on the design of wood-plastic composite (WPC) products. In this study, recycled high-density polyethylene plastic was used as the matrix, wood powder was used as the filler, different types of nanofillers and self-synthesized nanofiller treatment agents were added, and the twin-screw extrusion granulation method was used to prepare nano-WPC materials. The effects of different types of nanofillers on the mechanical properties of nano-WPC materials were investigated, and the cross-sectional structures of the materials were analyzed by scanning electron microscopy. The results showed that nanofiller treatment agents improved the interface compatibility of the materials. When the treatment agent content reached 2.5% and the nano-montmorillonite content reached 10%, the mechanical properties of the material reach their maximum values.

Development and Evaluation of Mechanical Properties of Al/Ilmenite Nanocomposite

2014 ◽  
Vol 704 ◽  
pp. 32-38
Author(s):  
Lanka Rasidhar ◽  
A. Rama Krishna ◽  
Ch. Srinivasa Rao ◽  
K. Vijaya Lakshmi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Secondary Phase ◽  
Stir Casting ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron

In the present investigation, microstructure and mechanical properties of nanocomposites fabricated via stir casting were evaluated. The composites were based on Al (99.7) reinforced with ilmenite nanoparticles. The characterization of the nanoparticles and nanocomposites was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) facilities. Microstructure of specimens show that reasonable distribution of FeTiO3 nanoparticles in the matrix, secondary phase FeAl3 observed in the microstructure. Ultimate tensile strength and compression tests were carried out in order to identify the mechanical properties. The hardness of the composites is enhanced with the addition of nanoparticles. The optimum value for ultimate tensile and compression strength are obtained with the addition of 3 % ilmenite nanoparticles. Ductile fracture in tensile fractured samples was observed by fractrography examination.

Mechanical properties of the collagenous framework of skin in rats of different ages

1964 ◽  
Vol 206 (6) ◽  
pp. 1425-1429 ◽  
Author(s):  
Phyllis Fry ◽  
Margaret L. R. Harkness ◽  
R. D. Harkness
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Unit Area ◽  
Constant Load ◽  
Cross Sectional Area ◽  
Mechanical Resistance ◽  
Sectional Area ◽  
Cross Sectional ◽  
Constant Rate ◽  
Zero Time

The collagen content, tensile strength, and extensibility of the skin of rats have been examined in rats 3–85 weeks of age. Tensile strength calculated per unit cross-sectional area of collagen increased with age, the maximal value in the oldest group (5.5 kg/mm2 collagen) being about three times that in the youngest. The quantity present per unit area of surface also increased with age. An estimate of the total "surface mechanical resistance" obtained by multiplying collagen per unit area of skin and tensile strength rose continuously about twentyfold between the youngest to oldest of the groups. Application of a load produces after a time an elongation at constant rate ( K). Extensibility, measured by the ratio of this rate to length at zero time ( l0) obtained by extrapolation, and corrected to constant load of 100 g/mm2 cross-sectional area of collagen, was found to fall with age, the range being about eightyfold.

Microstructural examination of modified yttria stabilized zirconia by EM analytical techniques

1986 ◽  
Vol 44 ◽  
pp. 842-843
Author(s):  
W. W. Davison ◽  
R. C. Buchanan
Keyword(s):  
Mechanical Properties ◽  
Analytical Techniques ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Transmission Microscopy ◽  
Sintering Aid ◽  
Densification Temperature ◽  
Chemical Inertness ◽  
Scanning Transmission ◽  
Microstructural Examination

Yttria stabilized zirconia (YSZ) has become a significant technological material due to its high ionic conductivity, chemical inertness, and good mechanical properties. Temperatures on the order of 1700°C are required, however, to densify YSZ to the degree necessary for good electrical and mechanical properties. A technique for lowering the densification temperature is the addition of small amounts of material which facilitate the formation of a liquid phase at comparatively low temperatures. In this study, sintered microstructures obtained from the use of Al2O3 as a sintering aid were examined with scanning, transmission, and scanning transmission microscopy (SEM, TEM, and STEM).

Morphology and Mechanical Properties of Polyethylene Terephthalate/Ethylene Propylene Diene Monomer (PET/EPDM) in the Presence of Nanoclay

2020 ◽  
Vol 57 (3) ◽  
pp. 249-259
Author(s):  
Baifen Liu ◽  
Mohammad Mirjalili ◽  
Peiman Valipour ◽  
Sajad Porzal ◽  
shirin Nourbakhsh
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Thermal Destruction ◽  
Processing Temperature ◽  
Tem Analysis ◽  
Maximum Stiffness ◽  
Cloisite 30B ◽  
Nano Clay ◽  
The Matrix ◽  
Sample Maximum

This research deals with the mechanical properties, microstructure, and interrelations of triple nanocomposite based on PET/EPDM/Nanoclay. These properties were examined in different percentages of PET/EPDM blend with compatibilizer (Styrene-Ethylene/Butylene-Styrene)-G-(Maleic anhydrate) (SEBS-g-MAH). Results showed that the addition of 15% SEBS-g-MAH improved the toughness and impact strength of this nanocomposite. SEM micrographs indicated the most stable fuzzy microstructure in a 50/50 mixture of scattered phases of EPDM/SEBS-g-MAH. The effects of percentages of 1, 3, 5, 7 nanoclay Cloisite 30B (C30B) on the improvement of the properties were evaluated. With the addition of nano clay, the toughness and impact strength was reduced. Thermal destruction of nanoclay in processing temperature led to the decreasing dispersion of clay plates in the matrix and a reduction in the distances of nano clay plates in the composite compared to pure nano clay. XRD and TEM analysis was used to demonstrate the results. By adding 1% of nanoclay to the optimal sample, maximum stiffness, and Impact strength, among other nanocomposites, was achieved.

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