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論文

Effect of extrusion ratio in hot-extrusion on kink deformation during compressive deformation in an $$alpha$$Mg/LPSO dual-phase magnesium alloy monitored by ${it in situ}$ neutron diffraction

Harjo, S.; Gong, W.; 相澤 一也; 川崎 卓郎; 山崎 倫昭*; 眞山 剛*; 河村 能人*

Materials Transactions, 64(4), p.766 - 773, 2023/02

 被引用回数:1 パーセンタイル:87.31(Materials Science, Multidisciplinary)

To elucidate the effect of extrusion ratio in hot-extrusion on the deformation behavior during compression of Mg$$_{97}$$Zn$$_{1}$$Y$$_{2}$$ alloy containing about 25-vol% long-period stacking ordered phase (LPSO) in the HCP structured $$alpha$$ matrix ($$alpha$$Mg), ${it in situ}$ neutron diffraction measurements were performed under compressive loading using four types of samples: as-cast and after hot extrusion at 623 K with extrusion ratios of 5.0, 7.5 and 12.5. The macroscopic yielding was observed to appear by the occurrence of basal slip of $$alpha$$Mg in the as-cast sample and at the onset of twinning in the hot extruded samples. The applied stress to initiate slip, twinning, and kinking increased by hot extrusion and then decreased with increasing extrusion ratio. LPSO shared higher stress than $$alpha$$Mg and the ratio to the strength increased as the extrusion ratio increased.

論文

${it In situ}$ investigation of the microstructure evolution in Long-Period-Stacking-Ordered (LPSO) magnesium alloys as a function of the temperature

M$'a$this, K.*; Drozdenko, D.*; N$'e$meth, G.*; Harjo, S.; Gong, W.*; 相澤 一也; 山崎 倫昭*; 河村 能人*

Frontiers in Materials (Internet), 6, p.270_1 - 270_9, 2019/11

 被引用回数:6 パーセンタイル:31.68(Materials Science, Multidisciplinary)

Deformation behavior of two Mg-Zn-Y magnesium alloys, having a different fraction of the long-period-stacking-ordered (LPSO) phase, has been investigated at room temperature and 200$$^{circ}$$C by a combination of ${it in situ}$ neutron diffraction (ND) and acoustic emission (AE) measurements. The results indicate that the twinning in the magnesium matrix and the kinking in the LPSO phase strongly depend on the composition of the material and the testing temperature. Further, active deformation mechanisms and particularly the load transfer from the magnesium matrix to the LPSO phase define the mechanical properties of the investigated alloys.

論文

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

細川 伸也*; 木村 耕治*; 山崎 倫昭*; 河村 能人*; 吉田 亨次*; 乾 雅祝*; 筒井 智嗣*; Baron, A. Q. R.*; 川北 至信; 伊藤 晋一*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

 被引用回数:3 パーセンタイル:16.87(Chemistry, Physical)

Inelastic X-ray scattering (IXS) was performed on polycrystalline Mg$$_{97}$$Zn$$_1$$Y$$_2$$ and Mg$$_{85}$$Zn$$_6$$Y$$_9$$ alloys with synchronized long-period stacking ordered (LPSO) phase for investigating the impurity effects in the microscopic elastic properties. Inelastic neutron scattering (INS) was also carried out on the former alloy. LA modes were clearly observed in the IXS spectra of both the LPSO alloys, while TA modes can mainly be detected in the second Brillouin zone. Broader inelastic signals and larger quasielastic peaks are characteristic due to the phonon scattering by the Zn/Y impurities. Only the TA excitation energies increase by adding the impurities, which indicates a harder stiffness of the bond angles relating to the L1$$_2$$-type clusters in the LPSO alloys. New dispersion-less excitation modes are observed at about 10 meV by adding the Zn/Y impurities. By comparing with the INS data, the contributions of the impurities to these excitations are discussed using differences in the scattering cross-sections between neutrons and X-rays.

口頭

引張変形中のMg$$_{97}$$Zn$$_{1}$$Y$$_{2}$$内の$$alpha$$MgとLPSO間の応力分配と押出比の関係

Harjo, S.; 相澤 一也; Gong, W.*; 川崎 卓郎; 山崎 倫昭*; 河村 能人*

no journal, , 

押出比が異なる高温押出したMg$$_{97}$$Zn$$_{1}$$Y$$_{2}$$合金を室温で引張変形させならその場中性子回折実験を行った。高温押出による$$alpha$$MgとLPSOの集合組織の変化及び変形中の両相間の相応力分配を調べて、強化機構を議論する。

口頭

押出比の異なるLPSO-Mg合金の圧縮変形中のその場中性子回折測定

Harjo, S.; 相澤 一也; 川崎 卓郎; Gong, W.; 山崎 倫昭*; 河村 能人*

no journal, , 

Mg$$_{97}$$Zn$$_1$$Y$$_2$$ alloy is a magnesium alloy consisting an $$alpha$$Mg phase as the matrix and a Long-Period Stacking Ordered (LPSO) phase with the volume fraction of about 25%. In situ neutron diffractions during compression at room temperature of Mg$$_{97}$$Zn$$_1$$Y$$_2$$ alloys in as-casted condition and hot-extruded conditions with the extrusion ratios of 5.0, 7.5 and 12.5 were conducted to elucidate the deformation mechanism after hot-extrusion. The evolutions of integrated intensities of diffraction peaks, lattice strains of individual constituent phases measured from neutron diffraction were plotted with the applied stress and strain, and twinning in $$alpha$$Mg and kinking in LPSO phase were discussed.

口頭

圧縮変形中のMg$$_{97}$$Zn$$_1$$Y$$_2$$内の$$alpha$$MgとLPSO間の応力分配と押出比の関係

Harjo, S.; 相澤 一也; Gong, W.; 川崎 卓郎; 山崎 倫昭*; 河村 能人*

no journal, , 

LPSO相が約25%含まれたMg$$_{97}$$Zn$$_1$$Y$$_2$$合金について、高温押出後に圧縮変形させながらin situ中性子回折によって$$alpha$$Mg相とLPSO相それぞれが分担する応力を調べ、押出比(R)を大きくした時のLPSO相の強度について解明した。高温押出によって$$alpha$$Mg相の降伏応力が増大したが、Rが5.0から12.5になると$$alpha$$Mg相の降伏応力が小さくなった。しかしながら、巨視の降伏近傍ではLPSOの相応力はRが大きくなるに伴い大きくなった。これは、LPSO相の強度がRの増加によって低下しないことを表している。

口頭

Tensile strengthening of a Mg alloy containing 25-vol% LPSO by hot extrusion revealed by neutron diffraction

Harjo, S.; Gong, W.; 相澤 一也; 川崎 卓郎; 山崎 倫昭*; 河村 能人*

no journal, , 

Interesting mechanical properties changes were found in Mg$$_{97}$$Zn$$_1$$Y$$_2$$ alloy containing about 25-vol% long-period stacking ordered phase (LPSO) in the HCP structured $$alpha$$ matrix ($$alpha$$Mg), by hot-extrusion. In situ neutron diffraction measurements during tensile loading were conducted on three Mg$$_{97}$$Zn$$_1$$Y$$_2$$ alloys with different processes: as-casted, and after hot-extrusion at 623 K with extrusion ratios of 5.0 and 12.5, to elucidate the relation between the changes in microstructure by hot-extrusion with the changes in mechanical property. The yield strength of $$alpha$$Mg increased by the hot-extrusion, but when the extrusion ratio increased the $$alpha$$Mg yield strength ironically decreased. LPSO was found to be strengthened monotonically as the extrusion ratio increased.

口頭

Deformation behavior during tension in a Mg alloy containing 25% LPSO with different extrusion ratios monitored by neutron diffraction

Harjo, S.; 相澤 一也; Gong, W.; 川崎 卓郎; 山崎 倫昭*; 河村 能人*

no journal, , 

The Mg$$_{97}$$Zn$$_1$$Y$$_2$$ alloy, a magnesium alloy with a duplex microstructure consisting of an $$alpha$$ phase ($$alpha$$Mg) and a long period stacking ordered phase (LPSO) of approximately 25 vol.%, showed high strength and high ductility after hot extrusion at 623 K. To understand tensile deformation behavior of each phase and effect of kinks to the strength of the alloy, we have performed in situ neutron diffraction measurements during tensile tests of the alloys in an as-cast condition and after extruded at 623 K with different extrusion ratios.

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