Rare Earth Addition

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Haitham El Kadiri - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Rare Earth Addition on {101̅2} twinning induced hardening in magnesium
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2018
    Co-Authors: A. Imandoust, Christopher D. Barrett, Haitham El Kadiri
    Abstract:

    Abstract We investigated the effect of Gd and Ce Additions in magnesium on sigmoidal hardening behavior associated with { 10 1 2 } twinning after extrusion. Compression along extrusion direction revealed that Rare Earth Additions enhance the flow stress, while 〈 c + a 〉 softening was expected. This phenomenon has been explained by the enhancement of 〈 c + a 〉 dislocations activity and the ensuing increase in forest hardening due to solute drag. It is expected that dislocation transmutation of basal to prismatic will be enhanced during { 10 1 2 } twin growth in Rare Earth containing alloys, which would exacerbate 〈 c + a 〉 entanglement with the dislocation forests inside the twins. Forest hardening events overcompensated for the softening effects from lowering the critical resolved shear stresses of 〈 c + a 〉 dislocations, and resulted in higher flow stress for the binary Rare Earth containing alloys.

  • effect of Rare Earth Addition on 1012 twinning induced hardening in magnesium
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2018
    Co-Authors: A. Imandoust, Christopher D. Barrett, Haitham El Kadiri
    Abstract:

    Abstract We investigated the effect of Gd and Ce Additions in magnesium on sigmoidal hardening behavior associated with { 10 1 2 } twinning after extrusion. Compression along extrusion direction revealed that Rare Earth Additions enhance the flow stress, while 〈 c + a 〉 softening was expected. This phenomenon has been explained by the enhancement of 〈 c + a 〉 dislocations activity and the ensuing increase in forest hardening due to solute drag. It is expected that dislocation transmutation of basal to prismatic will be enhanced during { 10 1 2 } twin growth in Rare Earth containing alloys, which would exacerbate 〈 c + a 〉 entanglement with the dislocation forests inside the twins. Forest hardening events overcompensated for the softening effects from lowering the critical resolved shear stresses of 〈 c + a 〉 dislocations, and resulted in higher flow stress for the binary Rare Earth containing alloys.

Yiyi Li - One of the best experts on this subject based on the ideXlab platform.

  • very high cycle fatigue behavior of bearing steel with Rare Earth Addition
    International Journal of Fatigue, 2020
    Co-Authors: Chaoyun Yang, Yikun Luan, Dianzhong Li, Yiyi Li, Naeem Ul Haq Tariq
    Abstract:

    Abstract This study aims to clarify the effect of Rare Earth (RE) Addition on the very high cycle fatigue (VHCF) behavior of high-carbon chromium bearing steel. For this purpose, ultrasonic tension-compression fatigue tests were carried out on specimens extracted from bearing steels with and without RE Addition. As a result, RE Addition can prolong the fatigue life of bearing steel over 10 times and improve the fatigue limit at 109 cycles by 9.4% from 720 MPa to 788 MPa, which mainly result from the modification of RE elements to common CaO-Al2O3-MgO-SiO2-CaS inclusions, forming complex RE inclusions and leading to the decrease of inclusion size and the volume fraction of inclusions in bearing steel with RE Addition. On the VHCF fracture of bearing steels with and without RE Addition, both internal cracking mode and interface cracking mode exist at inclusions. Compared with bearing steel with RE Addition, bearing steel without RE Addition exhibits a longer crack initiation life due to stronger internal binding force of complex inclusions and interfacial binding force between complex inclusions and the matrix. However, smaller complex RE inclusions make crack propagation life of the former significantly longer than that of the latter. In Addition, fine granular area (FGA) can be used to estimate the fatigue limit of different fatigue life in the VHCF regime and the fatigue limit at 109 cycles evaluated based on FGA indicates an error of around 2% with respect to the fatigue limit measured by staircase method.

  • study on transverse longitudinal fatigue properties and their effective inclusion size mechanism of hot rolled bearing steel with Rare Earth Addition
    International Journal of Fatigue, 2019
    Co-Authors: Chaoyun Yang, Yikun Luan, Dianzhong Li, Yiyi Li
    Abstract:

    Abstract This study mainly aims to clarify the effect of Rare Earth (RE) Addition on the fatigue properties of hot rolled high-carbon chromium bearing steel, especially crack initiation and propagation behavior induced by long strip type inclusions in the very high cycle fatigue (VHCF) regime. For this purpose, ultrasonic tension-compression fatigue tests were carried out on transverse and longitudinal specimens extracted from hot rolled bearing steels with and without RE Addition. As a result, complex inclusions, usually containing inner oxide and peripheral oxide-sulfide duplex inclusion as well as (Ca, Mn)S inclusion, dominate the fatigue property of high clean bearing steel though MnS inclusions may lead to early fatigue failure of transverse specimens and contribute to fatigue anisotropy. RE Addition can better improve longitudinal fatigue property of hot rolled bearing steel than transverse fatigue property by modifying common inclusions into complex RE inclusions, which deform easily during hot rolling to reduce the effective inclusion size (EIS) at fatigue source. In contrast with fatigue failure caused by inclusion particle indicating almost synchronous crack propagation in all directions from inclusion particle, the width of instant crack plays an dominating role in crack initiation and propagation process for fatigue failure induced by long strip type inclusion. Fine granular area (FGA) only exists on both sides of the wider part of inclusion strip, and the length-width ratio of instant crack may continuously decrease with crack propagation. Effective inclusion area and corresponding EIS can be determined from the perspective of crack initiation and propagation in the VHCF regime. For VHCF fracture surface with FGA, the effective inclusion area corresponds exactly to the inclusion area included in FGA.

Jianming Xu - One of the best experts on this subject based on the ideXlab platform.

  • effects of magnetic field and Rare Earth Addition on corrosion behavior of al 3 0 wt mg alloy
    Journal of Alloys and Compounds, 2017
    Co-Authors: Xin Zhang, Zehua Zhou, Zehua Wang, Jianming Xu
    Abstract:

    Abstract Effect of magnetic field and Rare Earth on the corrosion behavior of Al-3.0 wt%Mg alloy in 3.5 wt% NaCl solution was investigated by immersion test and electrochemical measurement. The results indicated that a horizontal magnetic field would increase the corrosion potential (E corr ), impede the growth of pitting holes and reduce the corrosion current density i corr and corrosion rate of Al-3.0 wt%Mg-xR E alloys. Proper content of R E would increase the corrosion resistance of Al-3.0 wt%Mg alloys. Excessive R E would enhance the effect of magnetic field on the pitting corrosion sensibility and increased the corrosion rate of Al-3.0 wt%Mg alloys due to the increase of the number and the size of the second phases.

  • Effects of Cerium and Lanthanum on the Corrosion Behavior of Al-3.0 wt.%Mg Alloy
    Journal of Materials Engineering and Performance, 2016
    Co-Authors: Xin Zhang, Zehua Zhou, Zehua Wang, Jianming Xu
    Abstract:

    Effects of Rare Earth elements (RE: cerium and lanthanum) on the corrosion behavior of Al-3.0 wt.%Mg alloy were investigated by electrochemical measurement and immersion test in 3.5 wt.% NaCl solution. The results indicated that a proper amount of Rare Earth (about 0.2 wt.%) could improve the corrosion resistance of Al-3.0 wt.%Mg alloy effectively, whereas that excessive Rare Earth Addition would increase the corrosion rate and reduce the corrosion resistance. The corrosion behavior of Al-3.0 wt.%Mg alloys in 3.5 wt.% NaCl solution showed typical characteristics of pitting corrosion at the position of second phases. The more and the bigger the second phases, the more and the larger the pitting holes.

Chaoyun Yang - One of the best experts on this subject based on the ideXlab platform.

  • very high cycle fatigue behavior of bearing steel with Rare Earth Addition
    International Journal of Fatigue, 2020
    Co-Authors: Chaoyun Yang, Yikun Luan, Dianzhong Li, Yiyi Li, Naeem Ul Haq Tariq
    Abstract:

    Abstract This study aims to clarify the effect of Rare Earth (RE) Addition on the very high cycle fatigue (VHCF) behavior of high-carbon chromium bearing steel. For this purpose, ultrasonic tension-compression fatigue tests were carried out on specimens extracted from bearing steels with and without RE Addition. As a result, RE Addition can prolong the fatigue life of bearing steel over 10 times and improve the fatigue limit at 109 cycles by 9.4% from 720 MPa to 788 MPa, which mainly result from the modification of RE elements to common CaO-Al2O3-MgO-SiO2-CaS inclusions, forming complex RE inclusions and leading to the decrease of inclusion size and the volume fraction of inclusions in bearing steel with RE Addition. On the VHCF fracture of bearing steels with and without RE Addition, both internal cracking mode and interface cracking mode exist at inclusions. Compared with bearing steel with RE Addition, bearing steel without RE Addition exhibits a longer crack initiation life due to stronger internal binding force of complex inclusions and interfacial binding force between complex inclusions and the matrix. However, smaller complex RE inclusions make crack propagation life of the former significantly longer than that of the latter. In Addition, fine granular area (FGA) can be used to estimate the fatigue limit of different fatigue life in the VHCF regime and the fatigue limit at 109 cycles evaluated based on FGA indicates an error of around 2% with respect to the fatigue limit measured by staircase method.

  • study on transverse longitudinal fatigue properties and their effective inclusion size mechanism of hot rolled bearing steel with Rare Earth Addition
    International Journal of Fatigue, 2019
    Co-Authors: Chaoyun Yang, Yikun Luan, Dianzhong Li, Yiyi Li
    Abstract:

    Abstract This study mainly aims to clarify the effect of Rare Earth (RE) Addition on the fatigue properties of hot rolled high-carbon chromium bearing steel, especially crack initiation and propagation behavior induced by long strip type inclusions in the very high cycle fatigue (VHCF) regime. For this purpose, ultrasonic tension-compression fatigue tests were carried out on transverse and longitudinal specimens extracted from hot rolled bearing steels with and without RE Addition. As a result, complex inclusions, usually containing inner oxide and peripheral oxide-sulfide duplex inclusion as well as (Ca, Mn)S inclusion, dominate the fatigue property of high clean bearing steel though MnS inclusions may lead to early fatigue failure of transverse specimens and contribute to fatigue anisotropy. RE Addition can better improve longitudinal fatigue property of hot rolled bearing steel than transverse fatigue property by modifying common inclusions into complex RE inclusions, which deform easily during hot rolling to reduce the effective inclusion size (EIS) at fatigue source. In contrast with fatigue failure caused by inclusion particle indicating almost synchronous crack propagation in all directions from inclusion particle, the width of instant crack plays an dominating role in crack initiation and propagation process for fatigue failure induced by long strip type inclusion. Fine granular area (FGA) only exists on both sides of the wider part of inclusion strip, and the length-width ratio of instant crack may continuously decrease with crack propagation. Effective inclusion area and corresponding EIS can be determined from the perspective of crack initiation and propagation in the VHCF regime. For VHCF fracture surface with FGA, the effective inclusion area corresponds exactly to the inclusion area included in FGA.

Kaishu Guan - One of the best experts on this subject based on the ideXlab platform.

  • effect of Rare Earth Addition on super hydrophilic property of tio2 sio2 composite film
    Materials Chemistry and Physics, 2005
    Co-Authors: Kaishu Guan
    Abstract:

    Abstract Effects of CeO 2 or/and La 2 O 3 Addition on photo-generated hydrophilicity of TiO 2 /SiO 2 film were investigated in this paper with the testing of X-ray diffraction (XRD), Fourier transform infRared (FTIR) spectroscopy, ultraviolet–visible spectroscopy (UV–vis) and scanning electron microscopy (SEM). It is found that appropriate amount of CeO 2 or/and La 2 O 3 is effective on the super-hydrophilic property of TiO 2 because of the increase of oxygen vacancies. The super-hydrophilic property of the composite film becomes better during UV irradiation and it can maintain for a long time in the dark with the synergetic effect of Rare Earth oxides and SiO 2 .

  • Effect of Rare Earth Addition on super-hydrophilic property of TiO2/SiO2 composite film
    Materials Chemistry and Physics, 2005
    Co-Authors: Kaishu Guan
    Abstract:

    Abstract Effects of CeO 2 or/and La 2 O 3 Addition on photo-generated hydrophilicity of TiO 2 /SiO 2 film were investigated in this paper with the testing of X-ray diffraction (XRD), Fourier transform infRared (FTIR) spectroscopy, ultraviolet–visible spectroscopy (UV–vis) and scanning electron microscopy (SEM). It is found that appropriate amount of CeO 2 or/and La 2 O 3 is effective on the super-hydrophilic property of TiO 2 because of the increase of oxygen vacancies. The super-hydrophilic property of the composite film becomes better during UV irradiation and it can maintain for a long time in the dark with the synergetic effect of Rare Earth oxides and SiO 2 .