EFFECT OF NI/TI RATIO ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF MO-DOPED NITIAL INTERMETALLICS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2694-2699 ◽  
Author(s):  
XIAOYUN SONG ◽  
YAN LI ◽  
SHUSUO LI
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Precipitation Hardening ◽  
Volume Fraction ◽  
Solid Solution Hardening ◽  
X Ray Diffraction ◽  
Hardening Effect ◽  
Rich Alloy ◽  
Increasing Temperature ◽  
Compressive Tests

The microstructures and mechanical properties of Ni 50- x Ti 43+ x Al 6 Mo 1 ( x = 0.5, 1, 1.5, 3.5, 5.5 and 7 at. %) alloys have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and compressive tests. We found that the variation of Ni / Ti ratio is the predominant reason for affecting the yield stress. The yield stress at room temperature of Ni -rich and Ti -rich alloys was higher than that of the equi-atomic alloy due to the strong solid solution hardening caused by the variation of Ni / Ti ratio. The size and volume fraction of Ti 2 Ni phase decreased with increasing Ni / Ti ratio. The yield stress at 600°C and 700°C increased with the increasing volume fraction of Ti 2 Ni phase due to the precipitation hardening effect. The precipitation hardening effect was weakened with increasing temperature. For the Ti -rich alloy deformed at 800°C, the yield stress deceased with the increasing of Ni / Ti ratio due to the reduced strength and unfavorable distribution of Ti 2 Ni .

Stress in Hydrogenated Microcrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Peiró ◽  
C. Voz ◽  
J. Bertomeu ◽  
J. Andreu ◽  
E. Martínez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Silicon Thin Films ◽  
Abrupt Changes

AbstractHydrogenated microcrystalline silicon films have been obtained by hot-wire chemical vapor deposition (HWCVD) in a silane and hydrogen mixture at low pressure (<5 × 10-2 mbar). The structure of the samples and the residual stress were characterised by X- ray diffraction (XRD). Raman spectroscopy was used to estimate the volume fraction of the crystalline phase, which is in the range of 86 % to 98%. The stress values range between 150 and -140 MPa. The mechanical properties were studied by nanoindentation. Unlike monocrystalline wafers, there is no evidence of abrupt changes in the force-penetration plot, which have been attributed to a pressure-induced phase transition. The hardness was 12.5 GPa for the best samples, which is close to that obtained for silicon wafers.

Biomimetic composites inspired by venous leaf

2017 ◽  
Vol 52 (3) ◽  
pp. 361-372 ◽  
Author(s):  
Gongdai Liu ◽  
R Ghosh ◽  
A Vaziri ◽  
A Hossieni ◽  
D Mousanezhad ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Composite Structures ◽  
Volume Fraction ◽  
Matrix Material ◽  
Poisson's Ratio ◽  
Fiber Volume ◽  
Young’S Moduli

A typical plant leaf can be idealized as a composite having three principal fibers: the central mid-fiber corresponding to the mid-rib, straight parallel secondary fibers attached to the mid-fiber representing the secondary veins, and then another set of parallel fibers emanating from the secondary fibers mimicking the tertiary fibers embedded in a matrix material. This paper introduces a biomimetic composite design inspired by the morphology of venous leafs and investigates the effects of venation morphologies on the in-plane mechanical properties of the biomimetic composites using finite element method. The mechanical properties such as Young’s moduli, Poisson’s ratio, and yield stress under uniaxial loading of the resultant composite structures was studied and the effect of different fiber architectures on these properties was investigated. To this end, two broad types of architectures were used both having similar central main fiber but differing in either having only secondary fibers or additional tertiary fibers. The fiber and matrix volume fractions were kept constant and a comparative parametric study was carried out by varying the inclination of the secondary fibers. The results show that the elastic modulus of composite in the direction of main fiber increases linearly with increasing the angle of the secondary fibers. Furthermore, the elastic modulus is enhanced if the secondary fibers are closed, which mimics composites with closed cellular fibers. In contrast, the elastic modulus of composites normal to the main fiber ( x direction) exponentially decreases with the increase of the angle of the secondary fibers and it is little affected by having secondary fibers closed. Similar results were obtained for the yield stress of the composites. The results also indicate that Poisson’s ratio linearly increases with the secondary fiber angle. The results also show that for a constant fiber volume fraction, addition of various tertiary fibers may not significantly enhance the mechanical properties of the composites. The mechanical properties of the composites are mainly dominated by the secondary fibers. Finally, a simple model was proposed to predict these behaviors.

scholarly journals Mechanical Properties of the Ternary L12 Compound Co3(Al,W) in Single and Polycrystalline Forms

2011 ◽  
Vol 278 ◽  
pp. 1-6 ◽  
Author(s):  
Haruyuki Inui ◽  
Takashi Oohashi ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
Katsushi Tanaka
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Elastic Constants ◽  
Solid Solution Hardening ◽  
Anomalous Increase ◽  
Thermally Activated ◽  
Cauchy Pressure ◽  
Slip Planes ◽  
Temperature Ranges ◽  
L12 Structure

The mechanical properties of Co3(Al,W) with the L12 structure have been investigated both in single and polycrystalline forms. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously calculated. When judged from the values of Poisson’s ratio, Cauchy pressure and ratio of shear modulus to bulk modulus (Gh/Bh), the ductility of Co3(Al,W) is expected to be sufficiently high. In the yield stress-temperature curve, a rapid decrease and an anomalous increase in yield stress is observed in the low and intermediate (1000-1100 K) temperature ranges, respectively. The former is concluded to be due to the solid-solution hardening effect while the latter is attributed to thermally activated cross-slip of APB-coupled a/2<110> superpartial dislocations from octahedral to cube slip planes.

Mechanical Properties of Biomimetic Leaf Composite

2016 ◽  
Author(s):  
Hamid Nayeb Hashemi ◽  
Gongdai Liu ◽  
Ashkan Vaziri ◽  
Masoud Olia ◽  
Ranajay Ghosh
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Composite Structures ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Poisson's Ratio ◽  
Closed Cell ◽  
Cell Architecture ◽  
The Matrix

In this paper, we mimic the venous morphology of a typical plant leaf into a fiber composite structure where the veins are replaced by stiff fibers and the rest of the leaf is idealized as an elastic perfectly plastic polymeric matrix. The variegated venations found in nature are idealized into three principal fibers — the central mid-fiber corresponding to the mid-rib, straight parallel secondary fibers attached to the mid-fiber representing the secondary veins and then another set of parallel fibers emanating from the secondary fibers mimicking the tertiary veins of a typical leaf. The tertiary fibers do not interconnect the secondary fibers in our present study. We carry out finite element (FE) based computational investigation of the mechanical properties such as Young’s moduli, Poisson’s ratio and yield stress under uniaxial loading of the resultant composite structures and study the effect of different fiber architectures. To this end, we use two broad types of architectures both having similar central main fiber but differing in either having only secondary fibers or additional tertiary fibers. The fiber and matrix volume fractions are kept constant and a comparative parametric study is carried out by varying the inclination of the secondary fibers. We find significant effect of fiber inclination on the overall mechanical properties of the composites with higher fiber angles transitioning the composite increasingly into a matrix-dominated response. We also find that in general, composites with only secondary fibers are stiffer with closed cell architecture of the secondary fibers. The closed cell architecture also arrested the yield stress decrease and Poisson’s ratio increase at higher fiber angles thereby mitigating the transition into the matrix dominated mode. The addition of tertiary fibers also had a pronounced effect in arresting this transition into the matrix dominated mode. However, it was found that indiscriminate addition of tertiary fibers may not provide desired additional stiffness for fixed volume fraction of constituents. In conclusion, introducing a leaf-mimicking topology in fiber architecture can provide significant additional degrees of tunability in design of these composite structures.

Microstructures and Various Properties of Hot-Extruded Mg-Zr-Ca Alloys for Biomedical Applications

2012 ◽  
Vol 232 ◽  
pp. 162-166 ◽  
Author(s):  
Ying Long Zhou ◽  
Dong Mei Luo ◽  
Yun Cang Li ◽  
Cui'e Wen ◽  
Peter D. Hodgson
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Biomedical Applications ◽  
Hot Extrusion ◽  
X Ray Diffraction ◽  
Cast Alloys ◽  
Orthopedic Applications ◽  
Potential Use ◽  
Compressive Tests

The microstructures, mechanical properties, corrosion behavior, and biocompatibility of hot-extruded Mg-Zr-Ca alloys have been investigated for potential use in orthopedic applications. The microstructures of the alloys are examined by X-ray diffraction analysis and optical microscopy. The mechanical properties of Mg-Zr-Ca alloys are determined from compressive tests, the corrosion behavior is studied using immersion tests, and biocompatibility is evaluated by cell growth factor using osteoblast-like SaOS2 cell. The experimental results indicate that the hot-extruded alloys have much higher compressive strength than the as-cast alloys and the human bone, and can offer good mechanical properties for orthopedic applications. The hot-extrusion significantly enhances corrosion resistance of the alloys. Among the alloys, the hot-extruded Mg-0.5Zr-1Ca and Mg-1Zr-1Ca alloys possess good combination of mechanical properties, corrosion resistance, and biocompatibility, suggesting that they have a great potential to be good candidates for orthopedic applications.

scholarly journals Structure-Function Relationships of the Vertebral Endplate

2021 ◽  
Author(s):  
Yuanqiao Wu ◽  
Elise Feng-i Morgan ◽  
Johnfredy Loaiza ◽  
Rohin Banerji ◽  
Olivia Rose Blouin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Yield Stress ◽  
Volume Fraction ◽  
Level Density ◽  
Micro Computed Tomography ◽  
Vertebral Endplate ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Apparent Stiffness

Background: Although deformation and fracture of the vertebral endplate have been implicated in spinal conditions such as vertebral fracture and disc degeneration, few biomechanical studies of this structure are available. The goal of this study was to quantify the mechanical behavior of the vertebral endplate. Methods: Eight-five rectangular specimens were dissected from the superior and/or inferior central endplates of human lumbar spine segments L1-L4. Micro-computed tomography (μCT) imaging, four-point-bend testing, and ashing were performed to quantify the apparent elastic modulus and yield stress (modulus and yield stress, respectively, of the porous vertebral endplate), tissue yield stress (yield stress of the tissue of the vertebral endplate, excluding pores), ultimate strain, fracture strain, bone volume fraction (BV/TV), bone mineral density (BMD), and various measures of tissue density and composition (tissue mineral density, ash fraction, and ash density). Regression was used to assess the dependence of mechanical properties on density and composition. Results: Wide variations in elastic and failure properties, and in density and tissue composition, were observed. BMD and BV/TV were good predictors of many of the apparent-level mechanical properties, including modulus, yield stress, and in the case of the inferior vertebral endplate, failure strains. Similar values of the mechanical properties were noted between superior and inferior vertebral endplates. In contrast to the dependence of apparent stiffness and strength on BMD and BV/TV, none of the mechanical properties depended on any of the tissue-level density measurements. Conclusion: The dependence of many of the mechanical properties of the vertebral endplate on BV/TV and BMD suggests possibilities for non-invasive assessment of how this region of the spine behaves during habitual and injurious loading. Further study of the non-mineral components of the endplate tissue is required to understand how the composition of this tissue may influence the overall mechanical behavior of the vertebral endplate.

Effect of annealing temperature on microstructure and mechanical properties of a Ti–18Zr–12.5Nb–2Sn (at.%) alloy

2018 ◽  
Vol 11 (05) ◽  
pp. 1850033 ◽  
Author(s):  
Shuanglei Li ◽  
Tae-Hyun Nam
Keyword(s):  
Mechanical Properties ◽  
Annealing Temperature ◽  
Fracture Strain ◽  
Rolled Plate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recovery Strain ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolled ◽  
Increasing Temperature

In this study, the effect of annealing temperature on microstructure and mechanical properties of a Ti–18Zr–12.5Nb–2Sn (at.%) alloy was investigated by using optical microscopy (OM), X-ray diffraction (XRD) measurement and tensile test. The cold-rolled plate was annealed at temperatures between 773[Formula: see text]K and 1173[Formula: see text]K. Recrystallization occurred in the specimen annealed at 873[Formula: see text]K. Grain size increased from 8[Formula: see text][Formula: see text]m to 80[Formula: see text][Formula: see text]m with increasing temperature from 873[Formula: see text]K to 1173[Formula: see text]K. The ultimate tensile strength decreased from 1590[Formula: see text]MPa to 806[Formula: see text]MPa with increasing annealing temperature from 773[Formula: see text]K to 973[Formula: see text]K, and then showed similar value in the specimens annealed at temperatures from 973[Formula: see text]K to 1173[Formula: see text]K. The fracture strain increased from 3.8% to 41.0% with increasing annealing temperature from 773[Formula: see text]K to 1173[Formula: see text]K due to the recovery and recrystallization. The recovery strain increased with increasing of annealing temperature attributed to the evolution of recrystallization texture.

Static X-Ray Scans on the Titanium Hydride (TiH2) Powder during Dehydrogenation

2013 ◽  
Vol 795 ◽  
pp. 124-127 ◽  
Author(s):  
Nur Farhana Hayazi ◽  
Yu Wang ◽  
Mohd Noor Mazlee ◽  
Sammy Lap Ip Chan
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Isothermal Heating ◽  
X Ray ◽  
Refinement Method ◽  
Increasing Temperature

This work investigates the dehydrogenation of TiH2 powder during isothermal heating at 600°C using the static x-ray scans of high temperature x-ray diffraction (XRD). As-received TiH2 powder with a particle size of 5 μm and purity of 99.1% was used for this measurement. With increasing temperature, phase transformations occurred because of dehydrogenation and it happened very fast. It was found that during the phase transformation of TiH2 to titanium, some transitional phases observed and occurred. This finding confirmed the in-situ determination of TiH2 powder dehydrogenation by using Rietveld Refinement Method from our previous research. This study is useful for the fabrication of titanium-based composites and titanium alloys from TiH2 powder because the different phases in TiH2 will affect the final mechanical properties in titanium.

The Mechanical Properties of Electroplated Cu Thin Films Measured by means of the Bulge Test Technique

2001 ◽  
Vol 695 ◽  
Author(s):  
Yong Xiang ◽  
Xi Chen ◽  
Joost J. Vlassak
Keyword(s):  
Mechanical Properties ◽  
Film Thickness ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Bulge Test ◽  
X Ray Diffraction ◽  
Test Technique ◽  
Cu Films ◽  
Analytical Formulae

ABSTRACTThe mechanical properties of freestanding electroplated Cu films were determined by measuring the deflection of Si-framed, pressurized membranes. The films were deformed under plane-strain conditions. The pressure-deflection data are converted into stress-strain curves by means of simple analytical formulae. The microstructure of the Cu films was characterized using scanning electron microscopy and x-ray diffraction. The yield stress, Young's modulus, and residual stress were determined as a function of film thickness and microstructure. Both yield stress and Young's modulus increase with decreasing film thickness and correlate well with changes in the microstructure and texture of the films.

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