Microstructure and mechanical properties of slowly cooled Zr66.4Nb6.4Cu10.5Ni8.7Al8.0 with ductile bcc phase

2002 ◽  
Vol 754 ◽  
Author(s):  
Uta Kühn ◽  
Jürgen Eckert ◽  
Norbert Mattern ◽  
Nicolle Radtke ◽  
Ludwig Schultz
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Alloy Composition ◽  
Glassy Matrix ◽  
Compression Tests ◽  
Copper Mold ◽  
Glass Forming ◽  
Injection Casting ◽  
Bcc Phase

ABSTRACTWe report about the preparation and properties of a Be-free Zr66.4Nb6.4Cu10.5Ni8.7Al8.0 alloy with a glassy or a nanocrystalline matrix and ductile bcc precipitates, which were developed with the aim to improve the mechanical properties. The samples were prepared in form of rods by injection casting into a copper mold. The phase formation as well as the resulting microstructure and the mechanical properties of the different samples have been investigated upon cooling from the melt at different quenching rates. The formation of the bcc phase embedded in a glassy matrix is strongly governed by the alloy composition and the actual cooling rate during solidification, because the glass forming ability is much lower compared to Zr-based alloys containing Be. Already small reductions in cooling rate lead to precipitation of additional crystalline phases. Compression tests reveal that the in-situ glassmatrix composite undergoes work hardening and plastic deformation prior to failure. Surprisingly, also a nanocrystalline matrix leads to high elastic strain values. These features significantly improve the mechanical behavior of the composites compared to the monolithic glass.

Effect of Zr addition on the glass-forming ability and mechanical properties of Ni–Nb alloy

2007 ◽  
Vol 22 (2) ◽  
pp. 453-459 ◽  
Author(s):  
Z.W. Zhu ◽  
H.F. Zhang ◽  
W.S. Sun ◽  
Z.Q. Hu
Keyword(s):  
Mechanical Properties ◽  
Glass Forming Ability ◽  
Compression Tests ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Zr Addition ◽  
Pattern Structures ◽  
Injection Casting ◽  
Zr Alloys

The effect of zirconium (Zr) addition on the glass-forming ability (GFA) and mechanical properties of the Ni61.5Nb38.5 alloy has been studied. The addition of Zr improves the GFA. When x = 5 for Ni61.5Nb38.5−xZrx (in at.%) alloys, the alloy exhibits the best GFA and can be cast into 3-mm-diameter amorphous samples by using the copper mold injection-casting method. Differential scanning calorimetry measurements indicated that the thermal parameters, such as Trg and γ, have not a good correlation with the GFA in the Ni–Nb–Zr alloys. Compression tests reveal that the addition of Zr just decreases the fracture strength slightly from 3.4 to 3 GPa and that all of the tested samples exhibit a little compressive plasticity of about 2%. When x = 9, the feature of the fracture surface indicates that the alloy has a tendency for transition from the ductile to the brittle. And delicate “dimple” and microscale vein pattern structures have been observed on it.

Microstructure, thermal stability and mechanical properties of slowly cooled Zr-based composites containing dendritic bcc phase precipitates

2003 ◽  
Vol 806 ◽  
Author(s):  
Nicolle Radtke ◽  
Jürgen Eckert ◽  
Uta Kühn ◽  
Mihai Stoica ◽  
Ludwig Schultz
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Plastic Strain ◽  
Yield Strength ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Homogeneous Distribution ◽  
Compression Tests ◽  
Scanning Calorimetry ◽  
Bcc Phase

ABSTRACTWe report on the microstructure, the thermal stability and the mechanical properties of slowly cooled Zr-Nb-Cu-Ni-Al alloys with ductile bcc phase precipitates embedded in a glassy or nanocrystalline matrix. The samples were prepared in form of rods by injection casting into a copper mold. The phase formation and the microstructure of the composite material were investigated by X-ray diffraction, EDX analysis and scanning and transmission electron microscopy. The thermal stability was examined by differential scanning calorimetry and the mechanical behavior was investigated by compression tests under quasistatic loading at room temperature. The formation of bcc phase dendrites and a glassy or nanocrystalline matrix is strongly governed by the alloy composition and the actual cooling rate during solidification. Besides, changes in composition and cooling rate lead to different volume fraction and size of the bcc phase precipitates and, hence, to different values of yield strength, elastic and plastic strain. The samples with nanocrystalline matrix show a homogeneous distribution of the bcc phase precipitates over the whole cross-section and exhibit higher yield strength and plastic strain than the samples containing an amorphous matrix. Illustrated by the presented results we show the possibility of obtaining tailored mechanical properties by control of composition and solidification conditions.

Enhanced plasticity in a Ti-based bulk metallic glass-forming alloy by in situ formation of a composite microstructure

2002 ◽  
Vol 17 (12) ◽  
pp. 3015-3018 ◽  
Author(s):  
G. He ◽  
W. Löser ◽  
J. Eckert ◽  
L. Schultz
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Room Temperature ◽  
Shear Bands ◽  
Temperature Deformation ◽  
Glassy Matrix ◽  
Glass Forming ◽  
Injection Casting ◽  
Composite Microstructure

A bulk metallic glass-forming Ti–Cu–Ni–Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hexagonal-close-packed-Ti solid solution precipitates and a few Ti3Sn, β –(Cu, Sn) grains dispersed in a glassy matrix. The composite microstructure can avoid the development of the highly localized shear bands typical for the room-temperature deformation of monolithic glasses. Instead, highly developed shear bands with evident protuberance are observed, resulting in significant yielding and homogeneous plastic deformation over the entire sample.

Phase Selection in Sub-Rapidly Solidified Au-20Sn Alloys

2015 ◽  
Vol 817 ◽  
pp. 325-330
Author(s):  
Yu Hai Qu ◽  
Kai Jin Yang ◽  
Yan Tian Zhou ◽  
Yong Mao ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Copper Mold ◽  
Cooling Rates ◽  
Phase Selection ◽  
Graphite Mold ◽  
Injection Casting ◽  
Rapidly Solidified ◽  
Ausn Phase

The sub-rapidly solidified Au-20Sn eutectic alloys were prepared by four different solidification pathways, such as, graphite mold conventional casting, graphite mold injection casting, copper mold injection casting, and water-cooled copper mold suction casting. The precipitating sequences of competing primary phases of sub-rapidly solidified Au-20Sn alloys with four different cooling rates were investigated. The results show that phase selection process is related to the cooling rates during sub-rapid solidification process. The primary ζ'-Au5Sn phase with developed dendrites precipitate at low cooling rate (2.4×10−4.2×102K/min) and the morphologies of the primary ζ'-Au5Sn change to rosette-like at higher cooling rate (9.0×103K/min). While the cooling rate reaches to 3.5×104K/min, the primary ζ'-Au5Sn phase can be suppressed but δ-AuSn phase will precipitate prior to the ζ'-Au5Sn phase. On the basis of the classical nucleation theory and transient nucleation theory, the process of competitive nucleation between the ζ'-Au5Sn phase and the δ-AuSn phase were analyzed for sub-rapid solidified Au-20Sn alloy. The theoretical calculations are consistent with the experimental investigations.

Metastable Phase Equilibria in Co-Deposited Ni1−xZrx Thin Films

1991 ◽  
Vol 230 ◽  
Author(s):  
J. B. Rubin ◽  
R. B. Schwarz
Keyword(s):  
Thin Films ◽  
Cooling Rate ◽  
Metastable Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Amorphous Structure ◽  
Nucleation Theory ◽  
Glass Forming ◽  
Constant Heating

AbstractWe determine the glass forming range (GFR) of co-deposited Ni1−xZrx (0 < x < 1) thin films by measuring their electrical resistance during in situ constant-heating-rate anneals. The measured GFR is continuous for 0.10 < x < 0.87. We calculate the GFR of Ni-Zr melts as a function of composition and cooling rate using homogeneous nucleation theory and a published CALPHAD-type thermodynamic modeling of the equilibrium phase diagram. Assuming that the main competition to the retention of the amorphous structure during the cooling of the liquid comes from the partitionless crystallization of the terminal solid solutions, we calculate that for dT/dt = 1012 K s−1, the GFR extends to x = 0.05 and x = 0.96. Better agreement with the measured values is obtained assuming a lower ‘effective’ cooling rate during the condensation of the films.

Correlation between the Enhanced Plasticity of Glassy Matrix Composites and the Volume Fraction, Size and Intrinsic Mechanical Property of Reinforcements

2014 ◽  
Vol 783-786 ◽  
pp. 1967-1970
Author(s):  
Z.H. Chu ◽  
Hidemi Kato ◽  
Guo Qiang Xie ◽  
D.R. Yan ◽  
Guang Yin Yuan
Keyword(s):  
Mechanical Properties ◽  
Metallic Glasses ◽  
Volume Fraction ◽  
Shear Bands ◽  
Ex Situ ◽  
Glassy Matrix ◽  
Matrix Composites ◽  
Micro Scale ◽  
Fraction Size

In recent years, bulk metallic glasses (BMGs) have received considerable attention due to their unique mechanical properties. However, the deformation of BMGs is highly localized in a few shear bands so that many of them exhibit poor plasticity. As such, more and more researchers have focused on improving the plasticity by in-situ or ex-situ introducing of nanoor micro-scale crystalline phases into the metallic glassy matrix in order to formation of multiple shear bands.

Fabrication of Aluminum/Aluminum Nitride Composites by Reactive Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 181-184
Author(s):  
Seung Hoon Yu ◽  
Kwang Seon Shin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Elevated Temperatures ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Processing Technique ◽  
Compression Tests ◽  
Composite Powders ◽  
Al Matrix Composites

Various reactions and the in-situ formation of new phases can occur during the mechanical alloying process. In the present study, Al powders were strengthened by AlN, using the in-situ processing technique during mechanical alloying. Differential thermal analysis and X-ray diffraction studies were carried out in order to examine the formation behavior of AlN. It was found that the precursors of AlN were formed in the Al powders and transformed to AlN at temperatures above 600oC. The hot extrusion process was utilized to consolidate the composite powders. The composite powders were canned in an Al can and then extruded at elevated temperatures. The microstructure of the extrusions was examined by SEM and TEM. In order to investigate the mechanical properties of the extrusions, compression tests and hardness measurements were carried out. It was found that the mechanical properties and the thermal stability of the Al/AlN composites were significantly greater than those of conventional Al matrix composites.

An Artificial Material for Simulating Champlain Clays

1973 ◽  
Vol 10 (3) ◽  
pp. 489-503 ◽  
Author(s):  
F. A. Tavenas ◽  
M. Roy ◽  
P. La Rochelle
Keyword(s):  
Mechanical Properties ◽  
Effective Stress ◽  
Sampling Technique ◽  
Model Material ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Failure Envelope ◽  
Synthetic Material ◽  
Strain Behavior

As part of an investigation on the behavior of Champlain clays, full scale penetrometer and vane tests had to be performed in the laboratory to observe the behavior of the soil during such tests. Since it was impossible to obtain samples of the necessary size, it was decided to develop a synthetic material which would model the mechanical properties of the Champlain clays.Such a model material has been defined. It consists of a mixture of kaolinite, bentonite, cement, and water. It is first shown to have a stress–strain behavior identical to that of the clay in unconfined compression tests, provided it is aged for 16 days. It is also shown to simulate very well all other mechanical properties of the Champlain clays, and more particularly the peculiar shape of the failure envelope in effective stress as well as the preconsolidation pressure.This material has been used successfully for laboratory penetrometer tests. It can also be used for the installation of instruments in situ or for the analysis of any testing or sampling technique.

scholarly journals Effect of Different Jackfruit Puree Concentrations on the Mechanical Properties of Jackfruit Frozen Confection

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Amiruddin Mat Johari ◽  
Nur Aliaa Abd Rahman ◽  
Roseliza Kadir Basha ◽  
Azhari Samsu Baharudin ◽  
Mohd Afandi P. Mohammed ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Room Temperature ◽  
Relaxation Test ◽  
Compression Stress ◽  
Compression Tests ◽  
Stress Relaxation Test ◽  
Test Device ◽  
Mindstorms Ev3

Jackfruit frozen confection has been mechanically characterised in situ by using compression tests. There are no available studies on the mechanical behaviour of jackfruit frozen confection.   The aim of this study is to identify the mechanical properties of jackfruit frozen confections formulated with different concentrations of jackfruit puree. In this study, the experimental analyses are conducted using a compression test device made from LEGO Mindstorms EV3. The portable device is placed inside a freezer to enable the measurements to be done in low temperatures (-20oC). This is to overcome the limitation of an actual texture analyser which can only be operated at room temperature. The mechanical properties of jackfruit frozen confections at different jackfruit puree concentrations (10%, 20% and 30%) are obtained using the tester and analysed. The tests conducted are uniaxial compression, stress relaxation test and multi-step stress relaxation test. It has been observed that frozen confection with 20% jackfruit puree concentration (JF20) is able to withstand a higher force of compression (27.79kPa) compared to the ones with 10% (JF10) and 30% (JF30) concentrations, at 21.15kPa and 10.48kPa, respectively. For stress relaxation test, JF30 has the highest increasing stress for a strain of 0.05 to 0.2 but it decreases at a strain of 0.3 to 0.4. The results of the multi-step relaxation test on JF30 show agreement with the other two tests where the stress decays starting from the 3rd step until the 5th step of the test. This study provides information on the behaviour of jackfruit frozen confection when subjected to compression and stress that imitates the movement during consumption.

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