Increasing Solidification Rate of M2 High-Speed Steel Ingot by Fusible Metal Mold

Ji, Yanliang; Zhang, Wei; Chen, Xiaoyang; Li, Jianguo

doi:10.1007/s40195-016-0398-x

Cited by 12 publications

(15 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For increasing thickness of the ZnO layer, we also observe a decrease of the MR to

2 %

for

t_{ZnO} = 20

nm,

0.5 %

(30 nm), and

0.06 %

(80 nm) at 2 K (). Compared to data reported in the literature (

1.38

and

1.12 %

at 90 K for

t_{ZnO} = 3

and 10 nm ()), our MR values are by a factor of two higher. We note that a tunneling magnetoresistive (TMR) effect can be safely excluded due to the large thicknesses of the ZnO layers of

t_{ZnO} \geq 15

nm.…”

Section: Spin Transport In Znocontrasting

confidence: 72%

“…Reports on electrical spin injection in ZnO, in general, are rare and mainly focus on technical aspects rather than fundamental spin‐dependent properties. To directly investigate the carrier spins in our ZnO thin films together with their spin relaxation, we performed electrical transport experiments in Ni/ZnO/Co spin valve multilayer structures ().…”

Section: Spin Transport In Znomentioning

confidence: 99%

See 1 more Smart Citation

Zinc oxide –From dilute magnetic doping to spin transport

Opel

Goennenwein

Althammer

et al. 2014

Physica Status Solidi (b)

View full text Add to dashboard Cite

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.During the past years, there has been renewed interest in the wide-bandgap II-VI semiconductor ZnO, triggered by promising prospects for spintronic applications. First, ferromagnetism was predicted for dilute magnetic doping. In a comprehensive investigation of ZnO:Co thin films based on the combined measurement of macroscopic and microscopic properties, we find no evidence for carrier-mediated itinerant ferromagnetism. Phase-pure, crystallographically excellent ZnO:Co is uniformly paramagnetic. Superparamagnetism arises when phase separation or defect formation occurs, due to nanometer-sized metallic precipitates. Other compounds like ZnO:(Li,Ni) and ZnO:Cu do not exhibit indication of ferromagnetism. Second, its small spin-orbit coupling and correspondingly large spin coherence length makes ZnO suitable for transporting or manipulating spins in spintronic devices. From optical pump/optical probe experiments, we find a spin dephasing time of the order of 15 ns at low temperatures, which we attribute to electrons bound to Al donors. In all-electrical magnetotransport measurements, we successfully create and detect a spin-polarized ensemble of electrons and transport this spin information across several nanometers. We derive a spin lifetime of 2.6 ns for these itinerant spins at low temperatures, corresponding well to results from an electrical pump/optical probe experiment.1 ZnO for spintronic applications Classical semiconductor-based devices rely on the controlled transport and storage of electrical charge. In semiconductor spintronics, however, both the electrons' charge and spin degree of freedom are exploited, providing fascinating perspectives for novel devices with improved performance. Moreover, since the spin degree of freedom usually is coupled much more weakly to the environment than the charge degree of freedom, spin-based devices are promising for future quantum devices making use of quantum superposition and entanglement. Therefore, both classical and quantum spintronics are rapidly growing areas of basic and applied research [1]. More than two decades ago, the exploitation of the spin degree of freedom in electronic devices started with the field of magnetoelectronics, in which ferromagnetic metals have been used in passive spin-dependent devices like spin valves, magnetic tunnel junctions, or magnetic sensors [2]. Magnetoelectronics then has been extended to the much broader field of spintronics, which is considered a replacement technology providing improved spin-active devices with the goal to encode information in single spins. The control of these spins (read, write, transport, and manipulate) is realized by magnetic fields, photonic fields, electric fields, or electric currents [1].With regard to materials and starting from metal-based devices in the late 1980s, the field of spintronics soon ex...

show abstract

“…For increasing thickness of the ZnO layer, we also observe a decrease of the MR to

2 %

for

t_{ZnO} = 20

nm,

0.5 %

(30 nm), and

0.06 %

(80 nm) at 2 K (). Compared to data reported in the literature (

1.38

and

1.12 %

at 90 K for

t_{ZnO} = 3

and 10 nm ()), our MR values are by a factor of two higher. We note that a tunneling magnetoresistive (TMR) effect can be safely excluded due to the large thicknesses of the ZnO layers of

t_{ZnO} \geq 15

nm.…”

Section: Spin Transport In Znocontrasting

confidence: 72%

Section: Spin Transport In Znomentioning

confidence: 99%

Zinc oxide –From dilute magnetic doping to spin transport

Opel

Goennenwein

Althammer

et al. 2014

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…ZnO is particularly interesting for spintronics as it has a large bandgap and small spin–orbit coupling (), promising long spin dephasing times. For this system, both electrical spin‐injection and time‐resolved magneto‐optical experiments have been conducted, the latter demonstrating spin coherence up to room temperature. Here, we show that in ZnO, the temperature dependence of the amplitude ratio of two separate spin species can easily be misinterpreted as a strongly temperature dependent

T_{2}^{*}

of a single ensemble, while the two spin species have

T_{2}^{*}

, which only weakly depend on temperature.…”

Section: Introductionmentioning

confidence: 99%

Unambiguous determination of spin dephasing times in ZnO by time‐resolved magneto‐optical pump–probe experiments

Kuhlen

Ledesch

Winter

et al. 2014

Physica Status Solidi (b)

View full text Add to dashboard Cite

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Time-resolved magneto-optics is a well-established optical pump-probe technique to generate and to probe spin coherence in semiconductors. By this method, spin dephasing times T * 2 can easily be determined if their values are comparable to the available pump-probe delays. If T * 2 exceeds the laser repetition time, however, resonant spin amplification (RSA) can equally be used to extract T * 2 . We demonstrate that in ZnO these techniques have several tripping hazards resulting in deceptive values for T * 2 and show how to avoid them. We show that the temperature dependence of the amplitude ratio of two separate spin species can easily be misinterpreted as a strongly temperature-dependent T * 2 of a single spin ensemble, while the two spin species have T * 2 values, which are nearly independent of temperature. Additionally, consecutive pump pulses can significantly diminish the spin polarization, which remains from previous pump pulses. While this barely affects T * 2 values extracted from delay line scans, it results in seemingly shorter T * 2 values in RSA.

show abstract

“…AISI M2 steel (Fe-0.9 C-6 W-5 Mo-4 Cr-2 V, wt%) is a very popular high-speed steel because of its good combination of hardness and wear resistance at high temperatures [1,2]. Traditionally, M2 high speed steel manufacturing includes two steps, namely the mold casting and subsequent hot working like forging and rolling, which can break the coarse carbides network and refine structure.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Microstructure of M2 Steel Fabricated by Continuous Casting and with a Sand Mould

Zhang

Zhao

Wang

et al. 2019

Metals

View full text Add to dashboard Cite

AISI M2 steel was smelted in a 150 kg medium-frequency induction furnace and cast to form round billets with a cross-section diameter of 100 mm via a vertical continuous caster and sand mold. The secondary dendrite arm spacing (λ2), cooling rates, permeability and size and distribution of grains and network carbides of the two billets were studied. The results show that the continuous casting process can effectively decrease the λ2 value, permeability and size of the grains and carbides and improve the distribution of the grains and carbides during solidification. The λ2 values of the billets cast with a sand mold and continuous caster are 37.34 μm and 21.14 μm, respectively, and the cooling rate is 3.6 K·s−1 and 12.0 K·s−1, respectively. The area fractions of carbides at the center of the billets cast with the sand mold and continuous caster are 0.24 and 0.16, respectively, and increase by 27.7% and 25.4%, respectively, compared with their average values. The average grain size of billets cast with the sand mold and continuous caster is 69.4 μm and 50.5 μm, respectively. Compared with the sand mold billet, the grain size at the center of the continuous casting billet is reduced by 25.5%. The relationship between the grain size and cooling rate is presented in this paper.

show abstract

Increasing Solidification Rate of M2 High-Speed Steel Ingot by Fusible Metal Mold

Cited by 12 publications

References 18 publications

Zinc oxide –From dilute magnetic doping to spin transport

Zinc oxide –From dilute magnetic doping to spin transport

Unambiguous determination of spin dephasing times in ZnO by time‐resolved magneto‐optical pump–probe experiments

Comparison of the Microstructure of M2 Steel Fabricated by Continuous Casting and with a Sand Mould

Contact Info

Product

Resources

About