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ú{}CNO‰reBžpwï Vol. 26 No. 2 2009 (117_121)
ÁWFÞ¿ ê±êk¥«Þ¿l
i´˜_¶j
Fe n‡àÌ
hbv`…[u@ðp¢½ Nd_
€À芶¬Æ‚ۥͭ»
ĺ
°EŒ_
GiEiR
ŸvEIÑ
êF
Formation of Metastable Phase with High Coercivity
in Nd_
Fe System by Drop Tube Processing
Hiroshi YONEMURA, Shuji AZUMO, Katsuhisa NAGAYAMA and Kazuhiko KURIBAYASHI
Abstract
The Nd_Fe and Nd_Fe_Al alloys were containerlessly solidiˆed by using two types of drop­tubes: short and long ones,
the free fall lengths of which are 3 m and 26 m, respectively. The diameters of as­dropped samples formed by using these
short and long drop­tubes are ranged 100_1000 and 100_2300 mms, respectively. The coercivities of the as­dropped Nd_
Fe_Al samples formed in the long drop­tube increased with decrease of the diameters, but in the samples with diameters
less than the critical one, the coercivities decreased whereas the saturation of the magnetization increased. The reason for
this phenomenon is ascribed to the formation of soft magnetic phases such as an amorphous phase due to the high cooling
rates. In Nd_Fe alloys, on the other hand, all of the as­dropped samples exhibited hard magnetic properties, Hc4.6
kOe. The microstructures of the as­dropped 90Nd_
10Fe samples consisted of primary a­Nd and the included metastable
phases. In as­dropped 70Nd_30Fe samples with diameters of 212_
300 mms, the microstructure consisted of primary
metastable phases and ˆne a­Nd. Considering the previous experimental results using the gas­jet electromagnetic levita­
tor, it can be concluded that the high coercivities of the as­dropped Nd_Fe samples are attributed to this ˆne metastable
phase and a­Nd.
Key Words: Containerless process, Short drop tube, Microgravity, Size eŠect, Non­equilibrium solidiˆcation
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é8_10)D
³eívZXÅÍ®Äðp¢é±ÆÈ­ZtðÃų
Nd2Fe14B Éã\³êé Nd_Fe n‡àÍC‚¢Û¥Íð
¹é½ßCeíÇ©çÌsƒ¨Ì¬ü¨æÑeíÇðDæ
¦·‡àƵÄmçêÄ¢é11_14)D˜ÒçÍC±êÜÅÉ
TCgÆ·ésÏêj¶¬Ì}§ªÂ\ÆÈèC‚ƒx¨
Nd_Fe ñ³‡àɨ¢Ä4.5 kOe ð´¦éÛ¥ÍðL·é
¿Ìn»â‚ßâxÌ­»ÉεÄÉßÄLøÈè@ÆÈ
€ÀèŠÌ¶¬ðñµÄ¨è3_5) CܽCA‚‹t@X
é1,2) DÈ©Åàhbv`…[u@ÍCnZŽ¿ð÷¬
`¬\ðå³¹éÚIÅ Al ðYÁµ½ Nd_Fe_Al O³
tHƵĬoµ©RŽº†É³eí©Â³Î¬ºÅÃÅ
‡àɨ¢ÄCA‚‹t@X¶¬Æ‚ۥͭ»ÌÖWÉ
³¹éè@Å èC” m ̎º—£ÅàmY‹æ[að
¢Ľ­Ì¤†ðñµÄ«½5_7)D{¤†Åͱêç
Ϧé±ÆÅlXÈ嫳̎¿ª¾çêé±ÆªÁ·Æ
̋Êð¥Ü¦ÄChbv`…[u@Éæé Nd_Fe n
³êéDÀÛC˜ÒçÍhbv`…[uàð He Åu·
‡àɨ¯éA‚‹t@X¨æрÀ芶¬ÉÖ·éÀ
·é±ÆÅC¼aª1000 mm öxÌå«ÈŽ¿É¨¢Äà
±ðs¢C\¢ðͨæÑ¥Cªè©ç Nd_Fe n‡àÉ
3 m Ì©RŽº—£Å³eíÃŪÂ\ÆÈé±Æðñ
¨¯é‚ۥ̀ÀèŠÌ¶¬É¢Ä̲¸EŸ¢ðÚ
µÄ¢é4)DܽC±Ìè@ÅÍCâp¬x͎¿a̸
IÆ·éD
­ÆÆàɝÁ·é±Æ©çC¬a̎¿ÅÍA‚‹t@
X é¢ÍA‚‹t@XÈÒÀèŠÌ¶¬àÂ\ÆÈ
éDÀÛChbv`…[u@Éæé Nd_Fe_B n‡àÌ
B. û
@
¼¬A[Nnð@ÉæèCNd (99.9 mass÷), Fe (99.99
ÅYHÆåwHw”Þ¿HwÈ §135_8548 Œžs]ŒæLF 3_7_5
Department of Materials Science, Faculty of Engineering, Shibaura Institute of Technology 3_
7_5 Toyosu, Koto­ku, Tokyo 135_
8548, Japan
(E­mail: nagayama—sic.shibaura­it.ac.jp)
\ 117 \
53
ĺ
°C¼
mass÷), Al (99.99 mas) ðp¢Ä Nd_Fe_Al O³‡à¨æ
…[uÀ±Åͼaª100`2000 mm öx̅óðæµC3
Ñ Nd_Fe ñ³‡àð컵½D‡àg¬ÆµÄÍC‚¢
m Ìhbv`…[uÀ±ÅÍ100`1000 mm öx̅ó
A‚‹t@X`¬\ðàÂ60Nd_30Fe_10Al g¬5) ÆCK
ðæµ½D¢¸êà¿Éæ誉µðÍðsÁ½D
XWFbg‚V@ðp¢½À±É¨¢ÄC‚ۥͭ»Ì
hbv`…[u@Éæè¾ç꽎¿ÍCõw°÷¾C
´öÆl¦çêé€ÀèŠÆ a­Nd ŠÌ¡ŠgD𦵽
SEM_EDS æègDÏ@yÑg¬ªÍðs¢C³çÉ Nd
Ÿ¤»g¬90Nd_10Fe3_5) ¨æÑߤ»g¬70Nd_30Fe3,4)
_Fe_Al Ž¿É¨¢ÄÍ DTA ÉæéMªÍ©ç‹»»ßö
Ƶ½D
ÌðÍðsÁ½DܽCVSM ðp¢½¥Cªè©ç€À
À±ÉÍ26 m Ì©RŽº”ðL·é26 m hbv`
芶¬¨æтۥͭ»É¢ğ¢µ½D
…[uÆ 3 m Ì©RŽº”ðL·é 3 m hbv`…[
C. ‹ÊyÑl@
uiFig. 1jÌñ@ðp¢CNd_Fe_Al Ž¿ÍOÒÅCÜ
½ Nd_Fe Ž¿ÍãÒÉæèÀ{µ½D26 m hbv`
C.A F@Nd_
C@Fe_
A@Al Ž¿ÌBFm hbv`…[uÀ
…[uÅÍCÎp»mY‹Ìæ[Ša1.0 mm ƵC`ƒ
±
Pa ÜÅrC
Fig. 2 É26 m hbv`…[uðp¢Ä³eíÃų
µ½ãC‚ƒx He Éu·µ½DêûC3 m hbv`
¹½ 60Nd_30Fe_10Al Ž¿Ì¥CqXeŠVXÈüiÅå
“o[àð^[{ªq|“vÉæè
1~10|3
…[uÅÍCæ[Ša100 mm öxÉÁHµ½§¾Îpm
óÁ¥êF15 kOejð¦·DܽCTable 1 É»êç̋
Y‹ðp¢C`ƒ“o[àð[^Š|“vÉæèrCãC
Ê ð Ü Æ ß ½ D a 2236 mm Ì Ž ¿ ( a ) Ì Û ¥ Í Hc Í 1.6
He KXÅu·µ½D2 íÞÌhbv`…[uÀ±Æ
kOe Æá¢l𦷪CÙÚ¯¶å«³ÌŽ¿(b)ÅÍ Hc
àCŽ¿ÍC‚ügÁMÉæèZ_ÈãÉÁM³ê½ãC
Í2.9 kOe ɝ嵽D±êÍCaª2000 mm ð´¦éæ
He KXÌÁ³Éæè`…[uàɬ˳ê©RŽº†É
¤Èå«ÈŽ¿ÅÍCâp¬xª¬³­Èé±ÆÉæè‚
Ãŵ½DȨCñûµ½Ž¿ÍC26 m Ìhbv`
ۥ͊Æ\tg¥«ŠÌ¼ûª¶¬µCµ©à»êçÌ
ÌÏäªâp¬xÉ˶µÄÏ»·é½ßÆl¦çêéD
êûCaª1300 mm (c)¨æÑ355`600 mm (d)̎¿Ì Hc
Í3.6 kOe öxƂ­ÈèCܽÈüÌ`ó©çÍ¥«Š
ÌPŠ»ª¦´³êéD·Èí¿ªŽ¿a̸­Éº¢
n[h¥«ŠÌ¶¬ªxzIÉÈÁ½±Æð¦µÄ¢éD
µ©µÈªçCaª125`355 mm Ƴçɬ³­ÈÁ½Ž
Table 1
Magnetic properties of 60Nd_30Fe_
10Al samples with
various diameters
Diameterimmj
Fig. 1
Schematic illustration of 3 m drop tube and high­speed
image of droplet ejection.
Fig. 2
54 J. Jpn. Soc. Microgravity Appl. Vol. 26 No. 2 2009
HcikOej
2236 mm
2186 mm
19.1
18.9
9.9
12.2
1.6
2.9
1308 mm
751 mm
19.7
19.5
14.5
16.3
3.6
3.6
600`355 mm
20
14.8
3.6
355`125 mm
38.4
12.3
1.5
M_H loops of 60Nd_30Fe_
10Al samples.
\ 118 \
Mmiemu/gj Mriemu/gj
Fe n‡à̀À芶¬Æ‚ۥͭ»
hbv`…[u@ðp¢½ Nd_
Fig. 5
Fig. 3
M_
H loops of 90Nd_10Fe samples with diameters: (a)
500`710 mm and (b) 212`300 mm.
Optical micrographs of 60Nd_30Fe_
10Al samples.
ÍặéD
Fig. 4 ÍCaª»ê¼ê850`1000 mm (a), 600`850 mm
(b), 355`600 mm (c)¨æÑ125`355 mm (d)Ž¿Ì DTA
ªè‹Êð¦µÄ¢éD·×Ä̎¿É¨¢ÄCA‚‹t
@XŠÌ\¢ÉaÉæéÆvíêéu[hÈs[NÆC
¯ŠÌ‹»»ÉæéärIs¢s[NÌñíÞÌ­M½ž
ªÏª³êéDu[hÈs[NÍCŽ¿a̸­C·È
í¿âp¬x̝ÁÆÆàÉå«­Èé±Æ©çC¬aÌ
Ž¿Å͂ÌϦÌA‚‹t@XŠÌ¶Ýª¦´³êéD
ܽCFig. 3 ÌgDÊ^Åq×½æ¤ÉCÁ¥IÈZ‹ó
gD͎¿a̸­ÆÆàÉ÷×ÉÈèܽ»ÌÌϦà
¸­·é±Æ©çCA‚‹t@XŠÍCÅIÃŔÆÈé
}gŠbNXÌæɶݷé±Æª¦´³êéD³çÉC
Nd_Fe_Al ɨ¯é˜ÒçÌKX‚VÀ±ÅÍCA‚‹t
Fig. 4
@XŠÆ¼Ì€ÀèŠÅ\¬³êÄ¢égDɨ¢Ä‚Û
DTA curves of 60Nd_
30Fe_10Al samples.
¥Íª¾çêÄ¢é±Æ©ç5_7)CãLÌ}gŠbNXg
DÉÍCKX‚VÀ±Å¾ç꽊ÆޗÌ\¢ðL·é
€À芪ÜÜêéÆl¦çêéDȨC±ÌA‚‹t@
¿(e)ÅÍCóÁ¥ê15 kOe ÅÌÅ奻ª38.4 emu/g
XŠÍCãÉq×½125`355 mm ̎¿É¨¯éÛ¥ÍÌ
ÆC¼ÌŽ¿ÆärµÄ 2 {ß­å«­ÈéÉà©©íç
áºÆ¥»ÌÁðà½çµ½V½È\tg¥«Š»Ìà
¸ Hc Í1.5 kOe ɸ­·éD±êÍCŽ¿a̸­Éº
ÌÆl¦çêéD
¤âp¬x̳çÈéåÉæèOa¥»Ì‚¢V½È\
C.B Nd_Fe ñ³‡àÌRm hbv`…[uÀ±
tg¥«Šª¶¬µ½±Æ𦴷éDȨChbv`
Fig. 5 ÉC3 m hbv`…[uðp¢Ä³eíÃų
…[uÀ±ÉæéeŽ¿aÉΞ·éâp¬xÍCNd_Fe
¹½ 90Nd_10Fe Ž¿Ì¥CqXeŠVXÈüiÅåóÁ
_B n‡àÉηé`MvZÉæèßçêĨèCaª
¥êF20 kOejð¦·D±Ì}©ç¾ç©Èæ¤ÉCŽ
1200 mm öx̎¿É¨¢ÄC3~10 K/s öxC400 mm
¿a500`710 mm ̎¿(a)yÑ212`300 mm ̎¿(b)Ì
̎¿É¨¢ÄÍ1.6~10 K/s öxÌâp¬xª¾çêé
¢¸êàCHc4.7 kOe öx̂ۥÍðL·éªCŽ¿
±Æªñ³êĨè C60Nd_30Fe_10Al Ž¿É¨¢Ä
(b)ÅÍCí¸©ÅÍ éª Nd_Fe_Al n‡àƯlÉC
3
4
9)
àCۥͪ¸­µ½aª125`355 mm ̎¿ÍC10 K/
‚ۥ͊ÆCŽ¿a̸­ÉºÁĶ¬µ½A‚‹t@
s Èã́¢âp¬xÉæèCV½È\tg¥«Š¶¬ª
XÆ̤¶ð¦´·éüȪÏ@³êéD
4
Fig. 6 ÉC3 m hbv`…[uųeíÃųê½
xzIÉÈÁ½àÌÆl¦çêéD
Fig. 3 ÍÛ¥Í̂¢1000 mm ȺÌa̎¿Ìõw°
70Nd_30Fe Ž¿Ì¥CqXeŠVXÈüiÅåóÁ¥êF
÷¾Ê^Å éDaª850`1000 mm ̎¿(a)ɨ¢Ä
20 kOejð¦·DȨCâp¬xª200 k/s öxÌKXW
ÍCZ‹ógDÆ}gŠbNX©çÈéñŠ\¢ªÏ@³
Fbg‚V@Å͉»ÆÈé Nd2Fe17 ŠÌ»oð}§·é
êéªCŽ¿a̸­Éº¢Z‹ógDÍ÷×»µÌϦ
±ÆÍ¢ïÅ Á½ªChbv`…[u@ÅÍa500`
J. Jpn. Soc. Microgravity Appl. Vol. 26 No. 2 2009
\ 119 \
55
ĺ
°C¼
710 mm ̎¿(a)¨æÑ212`300 mm ̎¿(b)Ì¢¸ê
½D±êÍCÈOÉñµ½KXWFbg‚V@ɨ¯é
àCHc4.7 kOe öx̂ۥÍð¦µCqXeŠVXÈ
90Nd_10Fe Ž¿Ì Curie ·xəµ­Cޗ̀ÀèŠ
üÌ`©çÍC‚Û¥ÍðS¤n[h¥«ŠÍPê̊Å
ª¶¬³ê½±Æ𦴷éD
Fig. 8 Éhbv`…[u@Éæé90Nd_10Fe Ž¿Ì
é±Æª„è³êéD
Fig. 7 ÍCFig. 5 ¨æÑ Fig. 6 Ư™ÌŽ¿Ì·x_¥
SEM œð¦·DŽ¿aÌÙÈé(ajCib)ÌoûÆàC}
CÈüÅ éDߤ»g¬70Nd_30Fe ÅͽtóÔ}ã
gŠbNXÍí¥« a­Nd ŠÅ èC‹»±EɀÀèŠ
©çÍ Nd2Fe17 ª‰»¶¬¨ÆÈéªC¼Ž¿ÆàÉC¯
Æ a­Nd Š©çÈé÷×gDª¶¬µÄ¢éDܽCŽ¿
ŠÌ¥CÏÔ·xÉΞ·é323 K tßɨ¢ÄC¥»Ì
a̸­ÆÆàɉ» a­Nd ŠÌ‹»±a͸­·éXü
Ï»ÍFßçê¸CCurie ·x͙µ­500 K Oãð¦µ
ªFßçê½DȨChbv`…[u@Éæé90Nd_
10Fe Ž¿Ì÷×gDÍC˜ÒçªÈOÉñµ½KXW
Fbg‚V@ɨ¯égD`Ô3,4) ÆÍC‹»±aðœ¢
Ä歗ĨèCâp¬x¨æÑßâx̝åªgDÌ÷
×»ðà½çµ½àÌƄ@³êéD
Fig. 9 ÉC3 m hbv`…[u@Éæè¾çê½a
500`710 mm Ì70Nd_30Fe Ž¿(a)¨æÑ212`300 mm Ì
Ž¿(b)Ì SEM œð¦·D¼Ž¿ÆàÉC¥Cªè‹Ê
ƯlC‰»¶¬¨ÆÈé Nd2Fe17 ŠÍÏ@³ê¸C€À
èŠÆ a­Nd Š©çÈ顊gDªúËóÉLªégDð
¦µ½DŽ¿(a)ɨ¢ÄÍC€ÀèŠÆ a­Nd ŠÌ‰
Fig. 6
Fig. 7
M_
H loops of 70Nd_30Fe samples with diameters: (a)
500`710 mm and (b) 212`300 mm.
Fig. 8
M_T curves of 90Nd_10Fe and 70Nd_
30Fe samples.
Fig. 9
Microstructures of 90Nd_10Fe samples with diameters:
(a) 500`710 mm and (b) 212`300 mm.
Microstructures of 70Nd_
30Fe samples with diameters: (a) 500`710 mm and (b) 212`300 mm.
56 J. Jpn. Soc. Microgravity Appl. Vol. 26 No. 2 2009
\ 120 \
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ÆÈé‹ÊÅ èC±êÍCÆ˔üÍÌ÷×È a­Nd Š
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1)
26 m Ìhbv`…[uÉæé60Nd_30Fe_10Al O
³‡à̳eíÃÅÀ±ÅÍCŽ¿a̸­ÆÆàÉî¥
«ŠªxzIÆÈèÛ¥ÍÍặéD±ê͎¿aÌá
ºÉº¤âp¬x̝Áª\tg¥«ŠÌA‚‹t@XŠ
̶¬ð£µ½±ÆÉæéÆl¦çêéD
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³eíÃÅÀ±ÅÍCŸ¤»g¬90Nd_10Fe ̉»Í a­
Nd Å èC‰»ÌüÍÉ÷×ȀÀ芪»oµC4.6
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J. Jpn. Soc. Microgravity Appl. Vol. 26 No. 2 2009
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