Bulk Amorphous Formation and Magnetic Properties of Nd-Fe-Co-Al Alloys by the New Gas Jet Flow Type Levitating Process

Abstract

The amorphous formation ability and the magnetic properties of Nd60Fe30xCoxAl10 (x 10, 15, 20 or 30) alloys in the containerless process were studied by the new gas jet flow type levitating process. The gas jet flow type levitating process enables solidification without any container wall by the inert gas jet. The samples were solidified at the cooling rate of around 100K/s. Then, the undercooling of samples exhibits high values (T 60{150K). From X-ray diffraction measurements, the Nd60Fe30xCoxAl10 samples exhibit a typical broad diffraction pattern for an amorphous structure. The DTA curves of x 10, 15 and 20 showed an exothermic peak due to the crystallization. That is, it was revealed that the Nd60Fe30xCoxAl10 samples formed bulk amorphous. Also, the coercivity is 1.6, 3.3 and 3.6 kOe for the Nd60Fe20Co10Al10, Nd60Fe15Co15Al10 and Nd60Fe10Co20Al10, respectively. From the thermomagnetic curves, the Curie temperature is determined to be 463, 482 and 482K for the Nd60Fe20Co10Al10, Nd60Fe15Co15Al10 and Nd60Fe10Co20Al10, respectively. In the M-H loops and the thermomagnetic curves, this difference between x 10 and x 15, 20 may depend on the microstructure. [doi:10.2320/matertrans.47.1568

Amorphous Formation and Magnetic Properties of Nd-Fe-Co-Al Alloys by Gas Flow Type Levitation Process

“…[1][2][3][4][5][6][7] Nd-Fe-Al amorphous alloy with a diameter up to 12 mm has been recently prepared and has hard magnetic properties at room temperature. 8) Also, the containerless process is expected to form bulk metallic glass by the utility of high undercooling because it minimizes the chances of sample surface contamination.…”

“…By using this process, we have reported about the amorphous formation ability, magnetic properties and effect of Co addition of Nd 60 -Fe x Co 30Àx Al 10 alloys (x ¼ 0, 10, 15 and 20). 7) However, the effect of amount of Nd hasn't been reported. This paper presents amorphous phase formation and magnetic properties of Nd-Fe-Co-Al alloys with different amount of Nd by the gas flow type electromagnetic levitation.…”

Undercooling Solidification and Magnetic Properties of Pr<SUB>90</SUB>Fe<SUB>10</SUB> Alloy Produced by the Gas Flow Levitation Method

“…Nd-Fe and Pr-Fe amorphous ribbons displayed hard magnetic properties at low temperatures. Additionally, Nd-Fe-Al and Nd-Fe-Co-Al amorphous alloys in bulk forms were found to exhibit high coercivity at room temperature 2,3,10,11) whereas these amorphous alloys in ribbon forms produced by a melt-spinning method exhibited soft magnetic properties. 10) Furthermore, the above-mentioned hard magnetic properties were not exhibited by the fully crystallized alloys.…”

“…In order to obtain more insight into the solidification behavior of undercooled melts, metastable phase formation depending on the undercooling, and magnetic properties of the metastable phase, we have investigated rare-earth-based alloys for the above-mentioned characteristics with the gas flow levitation process. 2,3) Rare-earth-based alloys have been investigated due to their unique magnetic properties, complex crystallization behavior, and high amorphous forming ability. [5][6][7][8][9][10][11][12] In particular, the magnetic properties and microstructure of Nd-Fe based alloys have been studied due to their complex microstructure, good magnetic properties, and relation to the Nd-Fe-B permanent magnets by many researchers.…”

“…[1][2][3] Further, aerodynamic levitation, a containerless process, is widely used to examine the amorphous forming ability and solidification behavior associated with undercooling. [2][3][4] The aerodynamic levitation process differs from the conventional electromagnetic levitation method and enables a high cooling rate because the sample can avoid electromagnetic heating during the cooling. Furthermore, in this process, the cooling rate can be altered easily by changing the cooling gas or the amount of the cooling gas.…”