scholarly journals Effect of Microstructure on the Dimensional Stability of Extruded Pure Aluminum

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4797
Author(s):  
Linlin Fu ◽  
Gaohui Wu ◽  
Chang Zhou ◽  
Ziyang Xiu ◽  
Wenshu Yang ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Dimensional Stability ◽  
High Performance ◽  
Annealing Temperature ◽  
Pure Aluminum ◽  
Extrusion Direction ◽  
Area Fraction ◽  
Navigation Systems ◽  
Average Grain Size ◽  
Equiaxed Grains

High-performance extruded aluminum alloys with complex textures suffer significant dimension variation under environmental temperature fluctuations, dramatically decreasing the precision of navigation systems. This research mainly focuses on the effect of the texture of extruded pure aluminum on its dimensional stability after various annealing processes. The result reveals that a significant increment in the area fraction of recrystallized grains with <100> orientation and a decrement in the area fraction of grains with <111> orientation were found with increasing annealing temperature. Moreover, with the annealing temperature increasing from 150 °C to 400 °C, the residual plastic strain after twelve thermal cycles with a temperature range of 120 °C was changed from −1.6 × 10−5 to −4.5 × 10−5. The large amount of equiaxed grains with <100> orientation was formed in the microstructure of the extruded pure aluminum and the average grain size was decreased during thermal cycling. The area fraction of grain with <100> crystallographic orientation of the sample annealed at 400 °C after thermal cycling was 30.9% higher than annealed at 350 °C (23.7%) or at 150 °C (18.7%). It is attributed to the increase in the proportion of recrystallization grains with <100> direction as the annealing temperature increases, provided more nucleation sites for the formation of fine equiaxed grains with <100> orientation. The main orientation of the texture was rotated from parallel to <111> to parallel to <100> after thermal cycling. The change in the orientation of grains contributed to a change in interplanar spacing, which explains the change in the dimension along the extrusion direction during thermal cycling.

Giant Magnetoimpedance in Fe73.5Cu1Nb2V1Si13.5B9 Nanocrystalline Ribbons

2014 ◽  
Vol 809-810 ◽  
pp. 99-104 ◽  
Author(s):  
Huai Gu Hu ◽  
Yang Ming Hao ◽  
Chun Jing Gao ◽  
Yan Zhao Wu ◽  
Fei Fei Liang
Keyword(s):  
High Frequency ◽  
High Performance ◽  
Annealing Temperature ◽  
Low Cost ◽  
Low Frequency ◽  
Partial Substitution ◽  
Giant Magnetoimpedance ◽  
Giant Magnetoimpedance Effect ◽  
Average Grain Size ◽  
Optimum Annealing Temperature

In the present work, the giant magnetoimpedance effect has been found in Fe73.5Cu1Nb2V1Si13.5B9nanocrystalline ribbons. The optimum annealing temperature for obtaining largest GMI is about 550°C. Fe73.5Cu1Nb2V1Si13.5B9with average grain size of 15 nm after annealing at 550°C for 30 min presents a magnetoimpedance of-74% at 700 kHz under H=90 Oe. The MI effect at high frequency is due to the change of Z via the variation of permeability or the penetration depth under the external field. The positive magnetoimpedance ΔZ/Z is 36% and positive magnetoresistance ΔR/R is 79% at H= 10 Oe and f=5MHz. We observe a huge magnetoreactance ΔX/X of –375% at a very low frequency of 50 kHz, which is a magnetoinduction effect due to the movement of domain wall. The smaller GMI for nanocrystalline Fe73.5Cu1Nb2V1Si13.5B9ribbons annealed above 550°C is mainly connected with the decrease of permeability due to the precipitation of Fe2B phase in ribbons. Our results show that the partial substitution of expensive Nb by cheap V in FeCuNbSiB could be a successful way to prepare the GMI materials with high performance and low cost.

Solid-Phase Crystallization of Amorphous Si0.7Ge0.3/Si and Si/Si0.7Ge0.3 Bilayer Films on SiO2

1996 ◽  
Vol 424 ◽  
Author(s):  
Tae-Hoon Kim ◽  
Myung-Kwan Ryu ◽  
Jin-Won Kim ◽  
Chang-Soo Kim ◽  
Ki-Bum Kim
Keyword(s):  
Annealing Temperature ◽  
Defect Density ◽  
Solid Phase ◽  
Crystallization Rate ◽  
Grain Morphology ◽  
Solid Phase Crystallization ◽  
Bilayer Films ◽  
Average Grain Size ◽  
Average Size ◽  
Equiaxed Grains

AbstractWe have investigated the solid phase crystallization of a-(Si/Si0.7Ge0.3) and a-(Si0.7Ge0.3/Si) bilayer films deposited on SiO2 for an annealing temperature of 550 °C. It was found that, in case of a-(Si0.7Ge0 3/Si), nucleation of crystalline phases occurred at the free surface, while in a-(Si/Si0.7Ge0.3) crystalline phase nucleated at Si0.7Ge0.3/SiO2 interface. The crystallization rate of an a-(Si0.7Ge0.3/Si) is much slower than that of an a-(Si/Si0.7Ge0.3) films. After full crystallization, poly-(Si0.7Ge0.3/Si) has many equiaxed grains and the defect density of the upper Si0.7Ge0.3 was much lower than that of lower Si0.7 Ge0.3 in a poly-(Si/Si0.7Ge0.3) film whose grain morphology was elliptical. The average grain size of poly-(Si0.7Ge0.3/Si) was ˜7 μm and this film had strong (111) preferential orientation, while poly-(Si/Si0.7Ge0.3) had weak (311) or random oriented grains with the average size of˜0.3 μm.

scholarly journals Superplasticity at Intermediate Temperatures of ZK60 Magnesium Alloy Processed by Indirect Extrusion

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 606
Author(s):  
César Palacios-Trujillo ◽  
José Victoria-Hernández ◽  
David Hernández-Silva ◽  
Dietmar Letzig ◽  
Marco A. García-Bernal
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Deformation Mechanism ◽  
Extrusion Direction ◽  
Grain Boundary Sliding ◽  
Mg Alloys ◽  
Homogeneous Microstructure ◽  
Texture Measurement ◽  
Average Grain Size ◽  
Zk60 Magnesium Alloy

Magnesium alloys usually exhibit excellent superplasticity at high temperature. However, many Mg alloys have poor formation ability near room temperature. Therefore, preparation of Mg alloys with suitable microstructures to show low or intermediate temperature superplasticity is an important goal. In this work, the superplastic behavior at intermediate temperatures of a commercial ZK60 magnesium alloy processed by indirect extrusion was investigated. After extrusion, the alloy showed a refined and homogeneous microstructure with an average grain size of 4 ± 2 μm. Overall texture measurement indicated that the alloy showed a strong prismatic texture with the highest intensity oriented to pole ⟨101¯0⟩. A texture component ⟨1¯21¯1⟩ parallel to the extrusion direction was found; this type of texture is commonly observed in Mg alloys with rare earth additions. Tensile tests were performed at temperatures of 150, 200, and 250 °C at three strain rates of 10−2, 10−3, and 10−4 s−1. A very high ductility was found at 250 °C and 10−4 s−1, resulting in an elongation to failure of 464%. Based on calculations of the activation energy and on interpretation of the deformation mechanism map for magnesium alloys, it was concluded that grain boundary sliding (GBS) is the dominant deformation mechanism.

Crystallization of Amorphous Sputtered NiTi Shape-Memory Alloy Films

1995 ◽  
Vol 398 ◽  
Author(s):  
F.F. Gong ◽  
H.M. Shen ◽  
Y.N. Wang
Keyword(s):  
Shape Memory ◽  
Annealing Temperature ◽  
Optimum Shape ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
Initial Stage ◽  
Average Grain Size ◽  
Optimum Heat ◽  
Diffraction Patterns ◽  
Optimum Heat Treatment

ABSTRACTThe crystallization of amorphous sputtered NiTi films was investigated for selected heat treatments. From x-ray diffraction patterns, when the films were annealed below the crystallization temperature, the intensity of the broad maximum centered at 2θ = 43.5° increased with increasing the annealing temperature and time. When the films were annealed at 550°C for 0.5hr, parent B2 phase and Ni4Ti3 precipitates appeared. For annealing temperature above 700°C, the films showed embrittlement and volatilization. Therefore the optimum heat treatment for the optimum shape memory effect is found. The average grain size increased slowly in the initial stage of annealing but remained almost unchanged when the films were annealed for more than 1hr. This is because the grain boundary grooving caused by the titanium at a certain temperature volatilization seriously hinder the grain growth.

scholarly journals Palindromic sequence-targeted (PST) PCR: a rapid and efficient method for high-throughput gene characterization and genome walking

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ruslan Kalendar ◽  
Alexandr V. Shustov ◽  
Mervi M. Seppänen ◽  
Alan H. Schulman ◽  
Frederick L. Stoddard
Keyword(s):  
Thermal Cycling ◽  
Annealing Temperature ◽  
Phleum Pratense ◽  
Genome Walking ◽  
Palindromic Sequence ◽  
Linear Amplification ◽  
Gene Characterization ◽  
Intron 1 ◽  
Thermal Cycling Profile ◽  
Palindromic Sequences

AbstractGenome walking (GW) refers to the capture and sequencing of unknown regions in a long DNA molecule that are adjacent to a region with a known sequence. A novel PCR-based method, palindromic sequence-targeted PCR (PST-PCR), was developed. PST-PCR is based on a distinctive design of walking primers and special thermal cycling conditions. The walking primers (PST primers) match palindromic sequences (PST sites) that are randomly distributed in natural DNA. The PST primers have palindromic sequences at their 3′-ends. Upstream of the palindromes there is a degenerate sequence (8–12 nucleotides long); defined adapters are present at the 5′-termini. The thermal cycling profile has a linear amplification phase and an exponential amplification phase differing in annealing temperature. Changing the annealing temperature to switch the amplification phases at a defined cycle controls the balance between sensitivity and specificity. In contrast to traditional genome walking methods, PST-PCR is rapid (two to three hours to produce GW fragments) as it uses only one or two PCR rounds. Using PST-PCR, previously unknown regions (the promoter and intron 1) of the VRN1 gene of Timothy-grass (Phleum pratense L.) were captured for sequencing. In our experience, PST-PCR had higher throughput and greater convenience in comparison to other GW methods.

Preparation and Magnetic Properties of Dense NiCuZn Ferrite by Spark Plasma Sintering

2008 ◽  
Vol 368-372 ◽  
pp. 601-603
Author(s):  
Xi Wei Qi ◽  
Ji Zhou ◽  
Zhen Xing Yue ◽  
Ming Ya Li ◽  
Xiu Mei Han
Keyword(s):  
Spark Plasma Sintering ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
Impurity Phase ◽  
Uniaxial Pressure ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
Nicuzn Ferrite

Dense NiCuZn ferrites consisting of fine grains were prepared by spark plasma sintering (SPS) at 750°C for 3 min under a uniaxial pressure of 15 MPa. The powders were densified to >95% of theoretical density by the SPS process, and the average grain size of the prepared NiCuZn ferrite was < 1 /m. The saturation magnetization of prepared specimens (without further annealing treatment) was approximate 50.54 emu/g, which was slightly smaller than that of 52.21 emu/g for specimens prepared by conventional sintering at 980°C for 4 h. Phase identifications indicated that prepared NiCuZn ferrite existed impurity phase (Cu2O), and Cu2O would gradually transform to CuO when annealing temperature increased.

scholarly journals Formation of the Equiaxed Grains in Pure Aluminum and Al-0.2%Cu Alloy Ingots

1970 ◽  
Vol 34 (8) ◽  
pp. 802-807
Author(s):  
Akira Suzuki ◽  
Jitsuhito Nakamura ◽  
Toshimasa Sakamoto
Keyword(s):  
Pure Aluminum ◽  
Cu Alloy ◽  
Equiaxed Grains

scholarly journals The Influence of Annealing Temperature on the Structure and Magnetic Properties of Nanocrystalline BiFeO3 Prepared by Sol–Gel Method

2021 ◽  
Author(s):  
T. Pikula ◽  
T. Szumiata ◽  
K. Siedliska ◽  
V. I. Mitsiuk ◽  
R. Panek ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Weak Ferromagnetism ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Average Grain Size ◽  
Spin Cycloid

AbstractIn this work, BiFeO3 powders were synthesized by a sol–gel method. The influence of annealing temperature on the structure and magnetic properties of the samples has been discussed. X-ray diffraction studies showed that the purest phase was formed in the temperature range of 400 °C to 550 °C and the samples annealed at a temperature below 550 °C were of nanocrystalline character. Mössbauer spectroscopy and magnetization measurements were used as complementary methods to investigate the magnetic state of the samples. In particular, the appearance of weak ferromagnetic properties, significant growth of magnetization, and spin-glass-like behavior were observed along with the drop of average grain size. Mössbauer spectra were fitted by the model assuming cycloidal modulation of spins arrangement and properties of the spin cycloid were determined and analyzed. Most importantly, it was proved that the spin cycloid does not disappear even in the case of the samples with a particle size well below the cycloid modulation period λ = 62 nm. Furthermore, the cycloid becomes more anharmonic as the grain size decreases. The possible origination of weak ferromagnetism of the nanocrystalline samples has also been discussed.

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