Self-diffusion of an asymmetric diblock copolymer above and below the order-to-disorder transition temperature

ABSTRACTSimultaneous grain boundary self-diffusion of iron and cobalt in FeCo was investigated in the B-kinetic regime by the radiotracer method combined with a serial sectioning technique over the temperature range 873-1133 K, which includes the A2-B2 bulk order-disorder transition temperature. This transition leads to a decrease in both iron and cobalt mass transport mainly owing to a change in the pre-exponential factor, but not in the diffusion activation energy. Moreover, the breaking point in the Arrhenius plots is observed below the bulk order-disorder transition temperature. In view of recent surface segregation studies on Fe-Co, and according to the Fe-Co phase diagram, the results are discussed assuming an iron segregation, which decreases the A2-B2 transition temperature in grain boundaries.

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Order−Disorder Transition Temperature Depression of a Diblock Copolymer Induced by the Addition of a Random Copolymer

Macromolecules ◽

10.1021/ma010593d ◽

2001 ◽

Vol 34 (22) ◽

pp. 7767-7772 ◽

Cited By ~ 4

Author(s):

Dae-Cheol Kim ◽

Hwan-Koo Lee ◽

Byeong-Hyeok Sohn ◽

Wang-Cheol Zin

Keyword(s):

Transition Temperature ◽

Diblock Copolymer ◽

Random Copolymer ◽

Disorder Transition ◽

Temperature Depression ◽

Disorder Transition Temperature

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Anomalous Difference in the Order−Disorder Transition Temperature Comparing a Symmetric Diblock Copolymer AB with Its Hetero-Four-Arm Star Analog A2B2

Macromolecules ◽

10.1021/ma9904060 ◽

1999 ◽

Vol 32 (22) ◽

pp. 7483-7495 ◽

Cited By ~ 16

Author(s):

D. M. A. Buzza ◽

I. W. Hamley ◽

A. H. Fzea ◽

M. Moniruzzaman ◽

J. B. Allgaier ◽

...

Keyword(s):

Transition Temperature ◽

Diblock Copolymer ◽

Disorder Transition ◽

Disorder Transition Temperature

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Alloying effect on the order–disorder transformation in tetragonal FeNi

Scientific Reports ◽

10.1038/s41598-021-84482-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Li-Yun Tian ◽

Oliver Gutfleisch ◽

Olle Eriksson ◽

Levente Vitos

Keyword(s):

Transition Temperature ◽

High Performance ◽

Density Functional ◽

Permanent Magnets ◽

Positive Impact ◽

Design Strategies ◽

Alloying Effect ◽

Functional Theory ◽

Disorder Transition ◽

Disorder Transition Temperature

AbstractTetragonal ($${\hbox{L1}}_{0}$$ L1 0 ) FeNi is a promising material for high-performance rare-earth-free permanent magnets. Pure tetragonal FeNi is very difficult to synthesize due to its low chemical order–disorder transition temperature ($$\approx {593}$$ ≈ 593 K), and thus one must consider alternative non-equilibrium processing routes and alloy design strategies that make the formation of tetragonal FeNi feasible. In this paper, we investigate by density functional theory as implemented in the exact muffin-tin orbitals method whether alloying FeNi with a suitable element can have a positive impact on the phase formation and ordering properties while largely maintaining its attractive intrinsic magnetic properties. We find that small amount of non-magnetic (Al and Ti) or magnetic (Cr and Co) elements increase the order–disorder transition temperature. Adding Mo to the Co-doped system further enhances the ordering temperature while the Curie temperature is decreased only by a few degrees. Our results show that alloying is a viable route to stabilizing the ordered tetragonal phase of FeNi.

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