Phase separation and stability of L21-type phase in Co 2(Cr1-xFex)(Ga1-yAly) alloys

Kosei Kobayashi; Ryosuke Kainuma; Kiyohito Ishida

doi:10.2320/matertrans.47.20

Phase separation and stability of L2₁-type phase in Co ₂(Cr_1-xFe_x)(Ga_1-yAl_y) alloys

Kosei Kobayashi, Ryosuke Kainuma, Kiyohito Ishida

ENG - Metallurgy

Research output: Contribution to journal › Article › peer-review

12 Citations (Scopus)

Abstract

The B2/L2₁ order-disorder transition and ferromagnetic/ paramagnetic transition temperatures in Co₂(Cr_1-xFe _x)(Ga_1-yAl_y) alloys were determined by differential scanning calorimetry and transmission electron microscopy. It was found that spinodal decomposition cannot be suppressed by quenching in the Al-rich portion of Co₂Cr(Ga_1-yAl_y) alloys, leading to lowering of Curie temperature T_c. The transition temperature T_t^B2/L21 from the B2 to L2₁-type phase decrease with increasing y for both the Co₂Cr(Ga _1-yAl_y) and Co₂Fe(Ga_1-yAl _y) alloy systems. The T_c in the Ga-rich portion of the L2₁-type Co₂Cr(Ga_1-yAl_y) alloy system is almost constant at about 480K, whereas that in the B2-type Co ₂Fe(Ga_1-yAl_y) alloy system slightly increases from about 1100 K to about 1170K. By extrapolation from the Ga-rich side of Co₂Cr(Ga_1-yAl_y) alloys, T_t ^B2/L21 and T_c of the metastable Co₂CrAl alloy were determined as 800 and 470 K, respectively. An optimal concentration area for obtaining excellent half-metallic properties and high stability of the L2₁-type phase in the Co₂(Cr_1-xFe _x)(Ga_1-yAl_y) alloys is proposed.

Original language	English
Pages (from-to)	20-24
Number of pages	5
Journal	Materials Transactions
Volume	47
Issue number	1
DOIs	https://doi.org/10.2320/matertrans.47.20
Publication status	Published - 2006 Jan

Keywords

Cobalt-chromium-iron-gallium-aluminum
Half-metallic ferromagnets
L2-type phase
Order-disorder transition
Spinodal decomposition

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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title = "Phase separation and stability of L21-type phase in Co 2(Cr1-xFex)(Ga1-yAly) alloys",

abstract = "The B2/L21 order-disorder transition and ferromagnetic/ paramagnetic transition temperatures in Co2(Cr1-xFe x)(Ga1-yAly) alloys were determined by differential scanning calorimetry and transmission electron microscopy. It was found that spinodal decomposition cannot be suppressed by quenching in the Al-rich portion of Co2Cr(Ga1-yAly) alloys, leading to lowering of Curie temperature Tc. The transition temperature TtB2/L21 from the B2 to L21-type phase decrease with increasing y for both the Co2Cr(Ga 1-yAly) and Co2Fe(Ga1-yAl y) alloy systems. The Tc in the Ga-rich portion of the L21-type Co2Cr(Ga1-yAly) alloy system is almost constant at about 480K, whereas that in the B2-type Co 2Fe(Ga1-yAly) alloy system slightly increases from about 1100 K to about 1170K. By extrapolation from the Ga-rich side of Co2Cr(Ga1-yAly) alloys, Tt B2/L21 and Tc of the metastable Co2CrAl alloy were determined as 800 and 470 K, respectively. An optimal concentration area for obtaining excellent half-metallic properties and high stability of the L21-type phase in the Co2(Cr1-xFe x)(Ga1-yAly) alloys is proposed.",

keywords = "Cobalt-chromium-iron-gallium-aluminum, Half-metallic ferromagnets, L2-type phase, Order-disorder transition, Spinodal decomposition",

author = "Kosei Kobayashi and Ryosuke Kainuma and Kiyohito Ishida",

year = "2006",

month = jan,

doi = "10.2320/matertrans.47.20",

language = "English",

volume = "47",

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T1 - Phase separation and stability of L21-type phase in Co 2(Cr1-xFex)(Ga1-yAly) alloys

AU - Kobayashi, Kosei

AU - Kainuma, Ryosuke

AU - Ishida, Kiyohito

PY - 2006/1

Y1 - 2006/1

N2 - The B2/L21 order-disorder transition and ferromagnetic/ paramagnetic transition temperatures in Co2(Cr1-xFe x)(Ga1-yAly) alloys were determined by differential scanning calorimetry and transmission electron microscopy. It was found that spinodal decomposition cannot be suppressed by quenching in the Al-rich portion of Co2Cr(Ga1-yAly) alloys, leading to lowering of Curie temperature Tc. The transition temperature TtB2/L21 from the B2 to L21-type phase decrease with increasing y for both the Co2Cr(Ga 1-yAly) and Co2Fe(Ga1-yAl y) alloy systems. The Tc in the Ga-rich portion of the L21-type Co2Cr(Ga1-yAly) alloy system is almost constant at about 480K, whereas that in the B2-type Co 2Fe(Ga1-yAly) alloy system slightly increases from about 1100 K to about 1170K. By extrapolation from the Ga-rich side of Co2Cr(Ga1-yAly) alloys, Tt B2/L21 and Tc of the metastable Co2CrAl alloy were determined as 800 and 470 K, respectively. An optimal concentration area for obtaining excellent half-metallic properties and high stability of the L21-type phase in the Co2(Cr1-xFe x)(Ga1-yAly) alloys is proposed.

AB - The B2/L21 order-disorder transition and ferromagnetic/ paramagnetic transition temperatures in Co2(Cr1-xFe x)(Ga1-yAly) alloys were determined by differential scanning calorimetry and transmission electron microscopy. It was found that spinodal decomposition cannot be suppressed by quenching in the Al-rich portion of Co2Cr(Ga1-yAly) alloys, leading to lowering of Curie temperature Tc. The transition temperature TtB2/L21 from the B2 to L21-type phase decrease with increasing y for both the Co2Cr(Ga 1-yAly) and Co2Fe(Ga1-yAl y) alloy systems. The Tc in the Ga-rich portion of the L21-type Co2Cr(Ga1-yAly) alloy system is almost constant at about 480K, whereas that in the B2-type Co 2Fe(Ga1-yAly) alloy system slightly increases from about 1100 K to about 1170K. By extrapolation from the Ga-rich side of Co2Cr(Ga1-yAly) alloys, Tt B2/L21 and Tc of the metastable Co2CrAl alloy were determined as 800 and 470 K, respectively. An optimal concentration area for obtaining excellent half-metallic properties and high stability of the L21-type phase in the Co2(Cr1-xFe x)(Ga1-yAly) alloys is proposed.

KW - Cobalt-chromium-iron-gallium-aluminum

KW - Half-metallic ferromagnets

KW - L2-type phase

KW - Order-disorder transition

KW - Spinodal decomposition

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