DOI : 10.5228/KSTP.2011.20.4.303
͑ G
穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊V
ZWZG
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橛列汊 決殯穢 匎暓凊 捊洛滎 穯匎汞 勦櫺洊砒 愕 砒刺洊決 笊旇 儆柢筚 櫶割
G
卆滆柣
#G
Visualization of Crack Propagation and Fracture Transition in Bulk Metallic Glass using Mechano-Luminescence
G
Ji Sik Kim
(Received March 17, 2011 / Revised April 12, 2011 / Accepted June 2, 2011) G
Abstract
Using a mechano-luminescent(ML) paint, which allows the visualization of fast propagating crack under conventional loading conditions, a catastrophic fracture mechanism associated to crack tip melting and wake bridging in bulk metallic glass, is described in this paper. Fracture occurs in two steps with, first, crack initiation from the mechanically machined sharp notch tip in a rectangular shaped compact tension specimen and melting of its tip due to intense shear deformation within very few deformation bands. Then, the crystalline phase in the glass matrix gradually converts the molten crack into a conventional bridged crack as it propagates.
G G
Key Words : Mechano-Luminescence(ML), Bulk Metallic Glass, Fracture Transition
41# ⇆# ᤊG G
⁞㏣Ἒ ゚㩫㰞 䞿⁞㦮 ἓ㤆 ₆⽎㩗㦒⪲ ╖┾䧞 䀾㟓䞮㡂 㡞゚ ‶㡊(Pre-crack) 㧦㼊☚ Ⱒ✺₆ 㠊
⩺㤎 ㈦ 㞚┞⧒ ザ⯎ ⼖䡫 Ṗ 㔲㠦 㧧㓺⩂㤊 䕢ᾊ 䡚㌗㦚 ⋮䌖⌊⸖⪲ ₆㫊㦮 㡆ῂ✺㦖 ⁏☚⪲
㩲䞲㩗㧎 䢮ἓ, 㯟, ⰺ㤆 ⌄㦖 ⼖䡫㏣☚ 䞮㠦㍲㦮 㩫㩗㧎 䘟Ⳋ⼖䡫 䕢ᾊ㧎㎇ Ṩ㦚 ‶㡊₎㧊㠦 ➆
⧒ 䁷㩫䞮Ệ⋮ 䢏㦖 㧒㩗㧎 䕢ᾊ㫆Ị㠦㍲㦮
㩫䢫䞲 ở⽊₆ 䕢ᾊ㧎㎇ Ṩ 䁷㩫㠦 Ⲏⶊ⯊ἶ 㧞┺[1, 2]. ╏㡆䞲 ἆὒ⪲ 㞚㰗₢㰖 㧧㓺⩂㤊 䕢ᾊ㔲㦮 ‶㡊₎㧊 ⼖䢪㠦 ➆⯎ 㩫䢫䞲 䕢ᾊ 㧎
㎇ Ṩ㦮 䁷㩫㧊⋮ ‶㡊 㩚䕢 㔲㠦 ⽊ἶ♮ἶ 㧞⓪
‶㡊 ぢ⧲䃃(Crack Branching) ⡦⓪ ⰂṖⲒ䔎 ぢⰂ 㰫(Ligament Bridging) 䡚㌗㠦 ╖䞲 㩫㎇㩗/㩫⨟㩗
䟊㍳㧊 㧊⬾㠊㰖㰖 ⴑ䞮ἶ 㧞⓪ 㔺㩫㧊┺[3~6].
㌗㑶䞲 ⶎ㩲㩦✺㦚 㧎㔳䞲 㧒 㡆ῂ㧦✺㦖 㾲
⁒ ✺㠊 ☯ 䡚㌗㠦 ╖䞲 ′ⳛ㦚 㥚䟊 䕢ᾊ 㔲
㌳♮⓪ ⼖䡫㡊㠦 㭒⳿䞮㡂 ‶㡊 㭒⼖㠦㍲ ㌳䞮
⓪ 㡊㩗 ⼖䢪⯒ ὖ㺆䞾㦒⪲㖾 䕢ᾊ 䞒⪲‶㡊
₎㧊㦮 ⼖䢪 ぢⰂ㰫 㦧⩻㥚 Ỗ㿲㦚 Ṗ㔲䢪 䞮⩺⓪ 㔲☚✺㦚 䞮ἶ 㧞┺. ⁎⩂⋮ 㔺䠮ἆὒ 㨂
⬢㦮 䕢ᾊ㠦 ➆⯎ 㡾☚ ㌗㔏㧊 ⁎┺㰖 䋂㰖 㞠㦒 Ⳇ, ⁒⽎㩗㦒⪲ 㡾☚ ⼖䢪㢖 䕢ᾊ㦧⩻ ぢⰂ㰫 㦧⩻ ㌂㧊㦮 㰗㩧㩗㧎 㦮㫊㎇㦚 ἆ㩫䞮⓪ ộ㧊
Ṗ⓻䞶 ㈦ 㞚┞⧒, 䃊Ⲫ⧒ 㧦㼊㦮 㩲㟓(䟊㌗☚
㾂㡗㏣☚ ❇) ✺⪲ 㧎䞮㡂 ㌂㔺㌗ 䕢ᾊ 䡚㌗㦚 㩫⨟䢪 䞮⓪◆ 㔺䕾䞮㡖┺[3~6].
㧊㢖⓪ ╂Ⰲ 㦧⩻㌗䌲⯒ 㔺㔲Ṛ㦒⪲ 䚲㔲 䞶 㑮 㧞⓪ 㞫ὧ 䗮㧎䔎(Mechano luminescent Paint)⯒
JG ᾦ㔶㩖㧦aG ἓ╖䞯ᾦG ⋮⏎㏢㨂Ὃ䞯SG G lTaGgUUG
ZW[
GV穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊G G⁞㏣Ἒ ゚㩫㰞 䞿⁞㦮 䚲Ⳋ㠦 㩗㣿䞮㡂 ỿ䞲
㏣☚⪲ 㩚䕢♮⓪ 䕢ᾊ ‶㡊㦚 Ṗ㔲䢪䞮ἶ 㧊⯒
㽞ἶ㏣ 䃊Ⲫ⧒⪲ ₆⪳䞶 ἓ㤆, ₆㫊㦮 䕢ᾊ 㔲䠮 㠦㍲ 䁷㩫䞶 㑮 㠜㠞▮ ṗ 㦧⩻㌗䌲㠦 ➆⯎ ‶㡊
₎㧊㦮 䁷㩫㦖 ⶒ⪶, ぢ⧲䃃 ぢⰂ㰫 㦧⩻ 䙂
❇ ┺㟧䞲 䕢ᾊ 䡚㌗㦮 㩫⨟㩗 䟊㍳㠦 䞚㑮㩗㧎 㩫⽊✺㦚 㿪Ṗ㩗㦒⪲ 䢫⽊䞶 㑮 㧞㦚 ộ㧊┺
[7~10]. ➆⧒㍲ ⽎ 㡆ῂ㠦㍲⓪ ⁏䧞 㾲⁒㠦 Ṳ♲
㞫ὧ 䗮㧎䔎⧒⓪ ₆⓻㎇ ㏢㨂⯒ 㧊㣿䞮㡂 ⻢䋂䡫
⁞㏣Ἒ ゚㩫㰞 (BMG) 㨂⬢㦮 ㏣ 䕢ᾊ ‶㡊 㩚䕢㠦 ➆⯎ 㩫䢫䞲 䕢ᾊ㧎㎇ Ṩ㦮 ⼖䢪㢖 ‶㡊 㩚䕢 㔲㠦 ἂ♮ἶ 㧞⓪ ┺㟧䞲 㨂⬢ 䡚㌗ ❇㦚
′ⳛ䟊 ⽊ἶ㧦 䞮㡖┺.
#
51# ⎎㚂᳓ᴿ#
⽎ 㡆ῂ㠦 ㌂㣿♲ Zr Ἒ ゚㩫㰞 䞿⁞㦖 LM1 㦮
㌗㣿 ⳛ㦒⪲ 㞢⩺㰚 䞿⁞㧊Ⳇ, Liquidmetal Technology
㌂⪲䎆 ₎㧊 100×⍞゚×⚦℮ 7mm ′ỿ㦮 䕦㨂 䡫䌲⪲ Ὃ 㞮┺. 䞿⁞㦖 900oC 㰚Ὃ 㞚䋂 㣿 䟊㠦 㦮䟊 㩲㫆 ♮㠞㦒Ⳇ, 䢪䞯㫆㎇㦖 Zr41.2Ti13.8
Cu12.5Ni10.0Be22.5⪲ 㞢⩺㪎 㧞┺. 䔏䧞 ☯ 䞿⁞㦖
⏨㦖 ゚㩫㰞 䡫㎇ ⓻⩻ὒ 㤆㑮䞲 ἓ☚, ṫ☚
⌊㔳㎇㦚 Ṗ㰖ἶ 㧞⓪ ộ㦒⪲ ⽊ἶ ♮ἶ 㧞㦒⋮, SEM 㫆㰗 ὖ㺆㠦 㦮䞮Ⳋ 䕦㨂 ⚦℮ 㡗䟻㦒⪲
㧎䞲 ⌟ṗ ⓻ Ṧ㏢⪲ 㟓 5% 䞒㥾 ⌊㣎㦮 10m 䋂₆㠦 䟊╏♮⓪ ゚ᾦ㩗 㫆╖䞲 ἆ㩫㌗✺㧊
゚㩫㰞 ₆㰖 ⌊㠦 㫊㨂 䞮㡖┺. 䞲䘎, 㞫ὧ 䗮㧎 䔎⓪ 㠦䙃㔲 Ἒ㡊㦮 ⩞㰚 ἓ䢪㩲㠦 (Eu, Dy)Ṗ 㻾Ṗ♲ SrAl2O4 Ⱖ㦚 䢒䞿䞮㡂 㩲㫆䞮㡖┺. ⽎ 㡆ῂ㠦 ㌂㣿♲ 㞫ὧ 䗮㧎䔎㦮 ἓ䢪 ㌗䌲㠦 ╖䞲 㡗 㥾(Young's Modulus)㦖 䢒䞿♲ 㠦䙃㔲㦮 㡆㰞
ἓ㰞 䔏㎇㠦 ➆⧒ 0.8~2.6GPa ⪲ 䁷㩫♮㠞㦒Ⳇ, 㧒㩗㦒⪲ 䕢ᾊ䡚㌗ Ṗ㔲䢪 䁷㩫㠦⓪ 㞫ὧ 䗮㧎 䔎㦮 㡗 㥾㧊 㡗䟻㦚 ⹎䂮㰖 㞠⓪ ộ㦒⪲ 㞢⩺㪎 㧞┺. ☯ 䗮㧎䔎✺㦖 㾲㫛㩗㦒⪲ CT 㔲䠮㣿 ⻢䋂
゚㩫㰞 䞿⁞ 㔲䘎㦮 䚲Ⳋ㠦 㞫ὧ 䗮㧎䔎⯒ ⚦℮
100 ജm ⪲ Fig. 1 (a)㢖 ṯ㦖 䡫䌲㦮 CT 㔲䠮㣿 㔲 䘎 㥚㠦 ☚䙂䞮㡂 Fig. 1 (b)㢖 ṯ㧊 㩲㧧 䞮㡖┺.
㾲㫛㩗㧎 CT 㔲䘎㠦 ╖䞲 ′ỿ㦖 ASTM E399[11]㦚 㩗㣿䞮㡂 㩞┾ ₆Ἒ ṖὋ㦚 䐋䞮㡂 㢚㎇♮㠞 㦒Ⳇ, ㌂ṗ 䡫䌲㦮 ῂ㼊㩗㧎 䂮㑮⓪ Fig. 1 (a)㢖 ṯ
┺. 䔏䧞, ‶㡊 㻾┾ 㥚⓪ 䕢ᾊ 㔲䠮㠦 㣪ῂ♮
⓪ ⋶䃊⪲㤊 ‶㡊 ㌳ 㩦㦚 ☚㧛䞮₆ 㥚䞮㡂
Fig. 1 Schematic drawing of a rectangular type compact tension specimen showing the dimension and shape
㩚 ṖὋ㠦 㦮䟊 ἓ 50m 㦮 ⋶䃊⪲㤊 㡞゚ ‶ 㡊㦚 㧎㥚㩗㦒⪲ ㌓㧛䞮㡖┺.
⽎ỿ㩗㧎 䕢ᾊ 㔲䠮㦚 㥚䟊 㞫ὧ 䗮㧎䔎Ṗ ☚䙂
♲ Fig. 1 (b)㦮 㔲䘎㦖 㞪㔺 㫆Ị㠦㍲ 䕢㧻 365nm㦮 ἶ⹖☚ 㧦㣎㍶㠦 10 ☯㞞 㡂₆(Excitation)䞲 䤚, 㧻 㧪ὧ(Long Phosphorescence) 䡚㌗㦚 Ṧ㏢㔲䋺₆ 㥚䞮㡂 㢚䢪㻮Ⰲ⯒ 1 㔺㔲䞮㡖┺. ㌗㑶䞲 㩚 㻮 Ⰲ⯒ Ệ䂲 CT 㔲䠮㣿 㔲䘎㦖 㧎㧻㔲䠮₆㦮 䞮㭧
ὒ 㧻䂮㠦 㧻㹿䞮㡂 䕢ᾊ 㔲䠮㦚 㔺㔲 䞮㡖┺.
㔺㩲㩗㧎 䕢ᾊ 㔲䠮㦖 ‶㡊 㩚䕢㏣☚⯒ ⻢䋂 ゚ 㩫㰞 㨂⬢㦮 㧧㓺⩂㤊 䕢ᾊ 㑮㭖㦒⪲ ⏨㧊₆ 㥚䞮㡂, 䋂⪲㓺䠺✲(Cross Head) ㏣☚⯒ ₆㫊㦮 䕢 ᾊ 䡚㌗ 䁷㩫㠦 ㌂㣿♮⓪ 䞮㭧 ㏣☚⽊┺ 㯳Ṗ♲
1mm/min⪲ 㑮䟟䞮㡖┺. 䕢ᾊ ☚㭧 ㌳♮⓪ ‶㡊 㻾┾ 䦪㩗 㡗㡃㦚 䙂䞾䞮⓪ 㩚㼊 ‶㡊 ἓ⪲⓪ 㽞ἶ㏣ 䢪㌗ ₆⪳ 㔲㓺䎲㦚 㧊㣿䞮㡂 㽞╏ 8000 䝚⩞㧚㦮 ㏣☚ 䞮㠦㍲ Ệ㔲㩗㧎 ′⳾(Macro Scale)
⪲ ₆⪳, ❪㰖䎎 ⁎Ⱂ 䕢㧒 䡫䌲⪲ 㩖㧻䞮㡖┺.
㔺䠮㠦 ㌂㣿♲ 䢪㌗₆⪳ 㔲㓺䎲㦖 㧒 㽞ἶ㏣
䃊Ⲫ⧒㠦 ┺㺚⍦ ◆㧊䎆 㡆ἆ㔳㦚 㺚䌳䞮㡂 䟊
穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊V
ZW\G
G
╏ 䢪㌗ ₆⪳ 㑲Ṛ㠦㍲㦮 㞫㩚 ⪲✲㎖⪲䎆 㠑 㠊㰖⓪ 䞮㭧 Ṩ㦚 䢪㌗ἆὒ㢖 㔺㔲Ṛ㦒⪲ 㡆☯䞾 㦒⪲㖾 ‶㡊₎㧊㠦 ➆⯎ 㦧⩻ 䢫╖ Ἒ㑮 Ṩ㦚 㩫 䢫䞮Ợ 䁷㼃 䞶 㑮 㧞┺. 㯟, 㧎㧻ἷ㍶㦒⪲䎆 㠑㠊㰚 㦧⩻ Ṩ㦮 ⼖䢪⪲䎆 㦧⩻䢫╖ Ἒ㑮 Ṩ 㦚 ASTM E399[11]㠦 ➆⧒ ❪㰖䎎 䃊Ⲫ⧒⪲ 䁷㩫
♲ ṗ ‶㡊₎㧊㠦 ╖䟊 㩫⨟㩗㦒⪲ Ἒ㌆䞮⓪ ộ 㧊 Ṗ⓻䞮☚⪳ ㍺Ἒ䞮㡖┺. Ⱎ㰖Ⱏ㦒⪲, 䕢ᾊ 䔏
㎇ ‶㡊 Ệ☯㠦 ⹎䂮⓪ ⹎㎎ 㫆㰗䞯㩗 㡗䟻㦚 㫆㌂䞮₆ 㥚䟊 䕢ᾊ 㔲䠮䘎㦮 ‶㡊 䦪㩗 㡗㡃㦚 SEM㦒⪲ ὖ㺆䞮㡖┺.
61# ൚ඦ# Ჹ# ඊⳚ#
614# ㎶ෞ㚮Ⅻ# ಪ⎆㛾#
Fig. 2⓪ ⻢䋂 ゚㩫㰞 䞿⁞ CT 㔲䘎㦮 䞮㭧 Ṗ
㏣☚⯒ 1mm/min.⪲ ⏨㧎 㧎㧻 㫆Ị 䞮㠦㍲ ㌳♮
⓪ 䕢ᾊ 䡚㌗㦚 㞫ὧ 䗮㧎䔎㠦 㦮䟊 2.5Psec.☯㞞 Ṗ㔲䢪䞲 ἆὒ㧊┺. ⁎Ⱂ㠦㍲ 㞢 㑮 㧞❅㧊 ⻢䋂
゚㩫㰞 䞿⁞㦮 䕢ᾊ⓪ ⚦ ┾Ἒ㦮 䢫㡆䧞 ῂ♮
⓪ ὒ㩫㦚 Ệ㼦 㰚䟟♮㠞┺. 㼁 ⻞㱎 ὒ㩫㦖 㩚䡫 㩗㧎 ぢⰂ㰫 䡚㌗㦚 㧒㦒䋺㰖 㞠⓪ 㨂⬢㦮 ‶㡊 㩚䕢 ὒ㩫㦒⪲㖾(Fig. 2㦮 (a)㠦㍲䎆 (h) ₢㰖),
₆Ἒ㩗㦒⪲ ṖὋ♲ ‶㡊 㻾┾㦒⪲䎆 㧒㩗㧎 㤦䡫㦮 ╖䃃䡫 㦧⩻㧻㧊 䡫㎇♮ἶ, ‶㡊㦮 㩚䕢㠦
➆⧒ 䋂₆Ṗ 㯳Ṗ ♮Ⳋ㍲ 㩚㰚䞮⓪ 䡫䌲⯒ ⽊㧎
┺. 㧊➢ ἶ㏣ 䃊Ⲫ⧒㦮 ₆⪳ ㏣☚Ṗ 㽞╏ 8000 䝚⩞㧚 㧊⸖⪲ ṗ ㌂㰚㦖 㟓 125sec.㦮 Ṛỿ㦒⪲
㾂㡗♮㠞┺. ➆⧒㍲ 㽞₆ ‶㡊 ㌳㦖 ╖⨋ 㑮 m/sec.㦮 ㏣☚⪲ ㌳♮Ⳇ 㟓 8 䝚⩞㧚㠦 Ỏ㼦 㔲 䘎 㭧Ṛ⯒ 䟻䟊 ╖Ṳ 7.4mm⯒ 㩦㰚㩗㦒⪲ ぢⰂ 㰫 㦧⩻㦮 ㌳ 㠜㧊 㩚䕢䞮㡖┺.
㧊䤚 㔲䘎㦖 ‶㡊 㻾┾㠦㍲㦮 ṫ⩻䞲 㦧⩻㧻 䡫㎇ὒ 䞾℮ ‶㡊 㩚㰚㠦 ➆⧒ ‶㡊 䤚 㠦
㌗╖㩗㦒⪲ ⌄㦖 㩫☚㦮 ぢⰂ㰫 㦧⩻㠦 䟊╏♮⓪
゚╖䃃 㦧⩻㧻㦚 ㌳ 㔲䋺⓪ 䡚㌗㦚 ⋮䌖⌊㠞┺
(Fig. 2㦮 (i)㠦㍲䎆 (s)₢㰖). 䔏䧞 ‶㡊㧊 㔲䘎㦮 䔏㩫 ₎㧊 ₢㰖 㩚䕢 䞮⓪ Fig. 2㦮 (i)㠦㍲䎆 (n)
₢㰖⓪ ‶㡊 䤚㦮 㤾㧊䋂 㡗㡃㧊 㩦㹾 ╂䞮 ἶ 㧞㦒⋮, ‶㡊㩚䕢Ṗ Ⲟ㿮 䤚㠦⓪ 㩦㰚㩗㦒⪲
ぢⰂ㰫 㡗㡃㦮 ₎㧊㢖 ṫ☚Ṗ ⹎㏢䞮⋮Ⱎ Ṧ㏢䞮
⓪ 䡚㌗㦚 ὖ㺆䞶 㑮 㧞┺. 㧊⩂䞲 䡚㌗㦖 㩚䡫㩗 㧎 ぢⰂ㰫 㦧⩻ ㌳ 䔏㎇㦒⪲㖾, 㞢⬾⹎⋮⯒ 䙂 䞾䞮㡂 ぢⰂ㰫 䡚㌗㦚 㧒㦒䋺⓪ ┺㑮㦮 ῂ㫆㣿
㎎⧒⹏ 㨂⬢㦮 䕢ᾊ 㔲 ‶㡊 䤚㠦㍲ ┺㑮 ὖ㺆
♮㠞┺[8, 9]. ٻٻ
┺Ⱒ ㌗㑶䞲 ⚦ Ṳ㦮 ‶㡊 㩚䤚 㦧⩻㧻㧊 ‶ 㡊 㻾┾ 㥚㠦㍲ 㭧㻿♮㠊 ⋮䌖⋮⸖⪲ ⽎ 㡆ῂ 㠦㍲⓪ 㭧㻿♲ ⚦ Ṳ㦮 㦧⩻㧻㦚 Ⰲ䞮ἶ 㩫䢫 䞲 ‶㡊㦮 㥚䂮⯒ ἆ㩫䞮₆ 㥚䞲 ⽊┺ 㩫ᾦ䞲 䢪
㌗ ㍳㧊 䞚㣪䞮㡖┺. 㧊⯒ 㥚䟊 ⽎ 㡆ῂ㠦㍲⓪ 㞫ὧ ㌂㰚㦚 ゚䔎ⱋ 䡫㔳 䕢㧒⪲ 㩖㧻䞲 ┺㦢, ‶ 㡊㦮 㩚㰚㦚 ₆⪳䞲 ṗṗ㦮 䢪㌗ 䕢㧒㠦 䙂䞾♮
⓪ 512×128 䞓㎖㦮 㩗⏏㼃(RGB; Red, Green, Blue) Ṩ㦚 㧓㠊 ✺㧚㦒⪲㖾 ㌗╖㩗㧎 㦧⩻ Ṩ 䙂⪲
⼖䢮 䤚 Fig. 3㠦 Ṗ㔲䢪♲ 㞫ὧ ㌂㰚ὒ 䞾℮ ☚㔲 䞮㡖┺. 㧊⩂䞲 㩗⏏㼃 Ṩ㦮 㑮㰗 䟻 㩗 Ṩ㦖 ṗ 㥚䂮㠦㍲㦮 ‶㡊 㩚/䤚㠦 㥶♲ 㦧⩻Ṩ㦮
㌗╖㩗㧎 䋂₆ 䙂⯒ 䚲㔲䞮Ợ ♲┺. 㧒㩗㦒⪲
Ṗ 䞮㭧ὒ 㞫ὧ ṫ☚⓪ 䐋㌗ 䌚㎇ 㡗㡃㠦㍲ 㰗
㍶㩗 ㌗ὖὖἚ⯒ ⽊㧊⓪ ộ㦒⪲ 㞢⩺㪎 㧞㦒⸖⪲,
⽎ 㡆ῂ㠦㍲㢖 ṯ㧊 㞫ὧ ṫ☚㦮 ┾㑲 㩗 Ṩ㧊
‶㡊 㡗䟻㠦㍲㦮 ㌗╖㩗㧎 㦧⩻ ⡦⓪ ⼖䡫㥾 Ἒ㌆㠦 ㌂㣿♮⓪ ộ㦖 㿿䧞 䌖╏ 䞮┺ 䞶 㑮 㧞┺.
➆⧒㍲ Fig. 3 㦖 ‶㡊 㩚䤚㠦㍲ ‶㡊 㩚㰚㠦 ➆
⯎ 㦧⩻ 䙂 ⼖䢪㠦 ╖䞲 ὒ㩫㦚 ⋮䌖⌊⓪ ἆὒ
⪲ ⽒ 㑮 㧞㦒Ⳇ, 䔏䧞, ‶㡊 㩚 䤚㦮 㦧⩻㧻
Ⰲ㢖 䞾℮ ‶㡊 㻾┾㦮 㩫䢫䞲 㥚䂮 ㍶㩫㠦 ⰺ 㤆 㥶㣿䞮Ợ ㌂㣿♶ 㑮 㧞┺. ⽎ 㡆ῂ㠦㍲⓪ 㤆㍶
䕢ᾊ ὒ㩫㠦㍲㦮 ⳛ䢫䞲 ‶㡊 ₎㧊⯒ ἆ㩫䞮₆ 㥚䟊, ṗ ⁎⧮䝚㠦㍲ ‶㡊㴓㦒⪲㦮 䙂 ἷ㍶㧊 ỿ䧞 䞮⧓䞮⓪ 㠊₾ 㰖㩦㦚 ‶㡊 㻾┾ 㥚䂮⪲
㍶㩫 䞮㡖┺. 䟊╏ 㥚䂮⓪, ‶㡊 㻾┾㠦㍲㦮 㦧⩻
㧻 䡫㌗㧊 ῂ 䡫䌲⪲ 㞢⩺㪎 㧞㦒⸖⪲, 㦧⩻ 䝚⪲
䕢㧒㦮 㾲╖㩦 㡺⯎㴓 㥚⯒ 㣒㴓㦒⪲ 㭧⽋ 㩗 㣿䞮㡂 ἆ㩫䞲 ‶㡊 㥚䂮㢖 ╖㼊⪲ 㧒䂮䞮㡖┺.
䔏䧞, ‶㡊 㻾┾㠦㍲㦮 㦧⩻ 䙂⯒ ὖ㺆䞲 ₆ 㫊㦮 㡆ῂ ἆὒ㠦㍲ Fig. 3 㠦㍲㻮⩒ ☯❇ 䥮☚ 䙂 䘦 ἷ㍶㦒⪲ 䎆 ἆ㩫♲ ‶㡊 㥚䂮㢖☚ ゚ᾦ 㩗 㧮 㧒䂮䞮㡖┺[7]. ➆⧒㍲ 㞫ὧ ₆㑶㦚 䕢ᾊ 䡚
㌗㠦 㩗㣿䞶 ἓ㤆 㩚㑶䞲 㢖 ṯ㧊 ┾㑲 㩗㠦 㦮䞲 㞫ὧ 䙂 Ⱒ㦒⪲☚ ⰺ䋂⪲ 㡗㡃㠦㍲㦮 㩫 䢫䞲 ‶㡊 㥚䂮 ㍶㩫㧊 Ṗ⓻䞾㦚 㞢 㑮 㧞㠞┺.
#
615# Ტ⇢⤚⩫# ㍣⇛# Ḯ⇇#
⽎ 㡆ῂ㠦㍲ 㞫ὧ 䢪㌗ ㍳㦒⪲䎆 ὖ㺆♲
⻢䋂䡫 ⁞㏣ ゚㩫㰞 ㏢㨂㠦㍲㦮 䕢ᾊ 䡚㌗㦖 ㌂ 㔺 㥶㌂䞲 䕢ᾊ 䔏㎇㦚 ⽊㧊⓪ 㧒㩗㧎 ῂ㫆㣿
㎎⧒⹏ 㨂⬢㠦㍲㦮 䕢ᾊ 㟧㌗ ἆὒ㢖⓪ ⳝ Ṗ㰖
ZW]
GV穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊G GFig. 2 Sequence of high speed ML images at a frame speed of 8000fps.
㩦㠦㍲ ⁒⽎㩗㧎 㹾㧊⯒ ⋮䌖⌊⓪◆, 㼁 ⻞㱎⪲
㎎⧒⹏ 㨂⬢㠦㍲⓪ ‶㡊㻾┾㠦㍲㦮 㦧⩻㧻 ㌳
㧊 ⰺ㤆 㩗㦒Ⳇ ぢⰂ㰫 䡚㌗㧊 ṫ䞮Ợ ⋮䌖⋲┺
⓪ 㩦㧊┺[8]. ⚦ ⻞㱎⓪ 㧒㩗㦒⪲ ῂ㫆㣿 ㎎⧒
⹏ ㏢㨂㦮 ἓ㤆 ‶㡊㧊 㔲䘎 ⊳₢㰖 㩚䕢♮ἶ ⋲ 䤚㠦 ぢⰂ㰫 㡗㡃㧊 ‶㡊 㻾┾⯒ 䟻䟊 㧊☯䞮 㡂 㾲㫛㩗㦒⪲⓪ ‶㡊 㻾┾㥚㠦 ☚╂䞲 䤚 ㌂
⧒㰖⓪ ὒ㩫㦚 Ệ䂮Ợ ♮⋮, ⻢䋂 ゚㩫㰞 䞿⁞㠦 㧞㠊 ‶㡊 㩚䕢⓪ 㔲䘎㦮 㟓 㩞 㩫☚⯒ 㩚䕢䞲 䤚㠦 㟓䞲 ぢⰂ㰫 㦧⩻㧻㧊 ㌳䞮㡂 ‶㡊ὒ 䞾
℮ 㩚㰚䞮㡖┺⓪ 㩦㧊┺[9].
㧊⩂䞲 㹾㧊⓪ ⽎ 㡆ῂ㠦㍲ ㌂㣿䞲 㟓 5%㦮 ἆ 㩫㰞㦚 䙂䞾䞮ἶ 㧞⓪ Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 ⻢ 䋂 ゚㩫㰞 䞿⁞㦮 ἓ㤆 ₆Ἒ㩗 䔏㎇㧊 ゚㩫㰞 䔏
㎇ὒ ἆ㩫㰞 䔏㎇㧊 ⼖䡫 ὒ㩫㠦 䢒㨂䞮㡂 ⋮䌖
⋾㦒⪲㖾 ṗṗ㦮 㤆㎎ ῂṚ㠦㍲ 䕢ᾊ ⳾✲㠦 ⼖ 䢪Ṗ ㌳䟞₆ ➢ⶎ㦒⪲ 㿪㩫♲┺[3~6]. 䕢ᾊ 䡚
㌗㦮 㩚㧊 ὒ㩫㦚 ⽊┺ Ⳋ⹖䧞 㫆㌂䞮₆ 㥚䞮㡂 㔺㔲䞲 Fig. 3 (a), (b)㦮 x100, (c)㦮 x500 (d)㦮
Fig. 3 Sequence of high speed ML images and its stress distribution converted from M-L
x2000 䢫╖ 䕢Ⳋ ὖ㺆 ἆὒ☚ ㌗㑶䞲 ⼖䡫 ⳾✲
㦮 ⼖䢪⯒ ⁏ⳛ䞮Ợ ⽊㡂㭒ἶ 㧞┺. 㤆㍶ Fig. 3(a) 㦮 ἓ㤆 㩚 ṖὋ ‶㡊㦮 㻾┾㦒⪲䎆 7.5mm ỆⰂ 㧊⌊㦮 䕢Ⳋ㡗㡃 ㌂㰚㦒⪲㖾 㞴㍲ 㠎 䞲 ぢⰂ㰫 䡚㌗㦮 ㌳ 㠜㧊 ┾㑲䞲 䡫䌲㦮 ‶㡊 㻾
┾ 㦧⩻㧻㦮 䡫㎇㠦 ➆⯎ 䕢ᾊ 㡗㡃㠦 䟊╏♲┺.
㌂㰚㠦㍲ ㌊䘊 ⽒ 㑮 㧞❅㧊 ゚㩫㰞 䞿⁞㦮 㭒♲
䕢ᾊ ₆ῂ㧎 㩚┾⺊✲㠦 㦮䞲 vein 䡫䌲㦮 䕢Ⳋ㧊 ὖ㺆 ♮㰖 㞠ἶ ㏢㎇ 㡊㠦 㦮䟊 ῃ㩗㦒⪲ 㣿㦋
♲ 䡫䌲㦮 䕢Ⳋ㦚 ⽊㡂 㭒ἶ 㧞┺. 㧊⓪ ㌗╖㩗㦒
⪲ ⰺ㤆 ⋶䃊⫃Ợ ₆Ἒ ṖὋ♲ ⏎䂮㠦 㦮䟊 ㏢㎇
⼖䡫㧊 ⁏☚⪲ 㩲䞲♲ 1~2Ṳ㦮 㩚┾⺊✲㠦 㰧㭧
♮㠞㦢㦚 㩲㔲䞮⓪ 㯳Ệ㧊Ⳇ, ☯㔲㠦 㧊⪲ 㧎䟊
‶㡊 㻾┾㠦㍲㦮 ṫ䞲 㦧⩻㧻 䡫㎇㧊 㣿㦋 䕢Ⳋ
㌳㠦 㦮䟊 㠋㩲♮㠞▮ ộ㦒⪲ 䕦┾♲┺. Ⳋ Fig. 3 (b), (c) (d)㦮 䕢ᾊ 䤚 㡗㡃 㯟, ぢⰂ㰫 䡚㌗㧊 ㌳♲ 㡗㡃㠦㍲㦮 䕢Ⳋ ㌂㰚㦖 㩚┾⺊✲
㠦 㦮䞲 vein 䡫䌲㦮 䕢Ⳋ㧊 ὖ㺆 ♮Ⳇ, 䔏䧞 ἆ㩫
㌗ ⁒㠦㍲ ┺㑮㦮 ┺㭧 㩚┾ ⺊✲ ✺㧊 ㌳♮
穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊V
ZW^G
G
㠊 ‶㡊㦮 Ὴἷ ‶㡊 㻾┾㦮 㦧⩻㧻 䡫㎇㦚 㯳Ṗ㔲䆆㦢㦚 㓓Ợ 㿪㩫䞶 㑮 㧞┺. 㯟, ⻢䋂 ゚ 㩫㰞 䞿⁞㦮 ἓ㤆 䐋㌗ 㧊⩂䞲 㡆㎇ ἆ㩫㌗㦮 ☚ 㧛㧊 ┺㭧 㩚┾ ⺊✲⯒ ㌳㔲䌊㦒⪲㖾 ‶㡊 ⚪ 䢪(Blunting) ぢ⧲䃃(Branching) 䡚㌗㦚 㧒㦒䋺 ἶ 㾲㫛㩗㦒⪲⓪ ⹎㟓䞲 ぢⰂ㰫 Ệ☯㦚 ‶㡊 䤚
㠦㍲ ☚㧛䞮Ợ ♮⓪ ộ㦒⪲ 䕦┾♲┺[1~6].
616# ൮⢫# ㍣⇛# Ḯ⇇#
Fig. 5(a) ⓪ ⽎ 㡆ῂ㠦㍲ 䡖㰚 ⻢䋂 ゚㩫㰞 䞿⁞ ㏢㨂㦮 䕢ᾊ㠦 ╖䞲 2 ┾Ἒ 㻲㧊 ὒ㩫㦚 ṫ☚䞯㩗 䁷Ⳋ㠦㍲ ⽊┺ 㩫⨟㩗㦒⪲ 䟊㍳䞮₆ 㥚䞮㡂 㞫ὧ ₆㑶㦚 㧊㣿䞮ἶ, 䢪㌗ 㻮Ⰲ♲ ◆㧊 䎆✺㦚 㩗㣿䞮㡂, 䁷㩫䞲 㦧⩻䢫╖ Ἒ㑮㦮 ⼖䢪
⯒ ‶㡊 ₎㧊㦮 ⼖䢪㠦 ➆⧒ ⋮䌖⌎ ⁎Ⱂ㧊┺.
䕢ᾊ㦮 㽞₆ ┾Ἒ㠦㍲ ☯ 㨂⬢㦮 ở⽊₆ 㧎㎇
Ṩ㦖 12MPam 㩫☚⪲ 㧒㩗㦒⪲ 㞢⩺㰚 㑮㭖ὒ
゚㔍䞮Ợ 䁷㩫 ♮㠞㦒⋮, 䕢ᾊṖ 㰚䟟♾㠦 ➆⧒
㼁 ⻞㱎 ┾Ἒ㠦㍲ 㟓 1/3 㑮㭖㧎 4MPam1/2 㩫☚
₢㰖 Ṧ㏢䞮㡖┺[6]. 㧊⓪ 䕢Ⳋ ὖ㺆㠦㍲☚ ✲⩂⌂
❅㧊 㼁 ⻞㱎 䕢ᾊ ὒ㩫㧊 䔏㩫 1~2 Ṳ㦮 㩚┾ ⺊
✲㠦 㰧㭧♮㠊 㧒㠊⋮ἶ 㧊⪲ 㧎䟊 ㌳♲ 㡊⪲
㧎䞮㡂 ☯ 㥚㦮 ゚㩫㰞 䞿⁞㧊 ὒ⌟ṗ 㞷㼊 㡗 㡃㡾☚ 㧊㌗㦒⪲ 㰚㧛䞾㦒⪲㖾 ‶㡊 㻾┾㠦㍲ 㣿 㦋♲ 䡫䌲㦮 䕢Ⳋ㧊 ㌳♮Ⳇ, ⁎ ἆὒ ở⽊₆ 䕢 ᾊ 㧎㎇㧊 ỿ䧞 㩖䞮♲ ộ㦒⪲ 㿪㩫♲┺. ⁎⩂
⋮ Ἒ㏣㩗㧎 ‶㡊㦮 㩚䕢⓪ 㣿㦋 㩚┾ ⺊✲㦮 㰚 䟟 ἓ⪲ ㌗㠦 㧞⓪ ἆ㩫㌗✺㧊 ⁎ 㣿㦋 㡾☚Ṗ
㌗╖㩗㦒⪲ ⏨㞚 ‶㡊㦮 㣿㦋 ㌗䌲 㩚䕢⯒ 䟊 䞶 ㈦Ⱒ 㞚┞⧒ ἆ㩫㌗㦮 㥚Ṗ ‶㡊 㩚䕢 䟻ὒ
Fig. 4 Fracture morphology of the BMG in (a) molten and (b), (c), (d) conventional surface region
G G G
Fig. 5 Measured stress intensity factor on the basis of mechanoluminescent analysis
ⰴ㰖㞠㦚 ἓ㤆 ⹎㎎䞲 ┺㭧 ⺊✲✺㦚 ㌳㔲䋺⸖
⪲ ‶㡊㦮 blunting ὒ 䞾℮ 㩚┾⺊✲㦮 ぢ⧲䃃 (Branching) 㦚 ㌳㔲䋺Ợ ♲┺. 䔏䧞 ‶㡊 㩚㰚 㠦 ➆⯎ 㨂⬢㦮 㿫㩗♲ 䌚㎇㠦⍞㰖 Ṧ㏢Ṗ 㧊⩂
䞲 ゚ 㣿㦋 䕢ᾊ 䡚㌗㦚 ▪㤇 㫆㧻䞮Ợ ♮⸖⪲,
⁎ ἆὒ ỿ䧞 Ṧ㏢♲ ☯ 㨂⬢㦮 㦧⩻䢫╖ Ἒ㑮 Ṩ㧊 䐋㌗㩗㧎 㑮㭖㦮 12MPam1/2⯒ 䣢⽋䞮Ợ ♮
⓪ ộ㦒⪲ 䕦┾♲┺. 㧊⩂䞲 Fig. 5 㦮 䁷㩫 ἆὒ⓪
₆⽎㩗㦒⪲ ⽎ 㡆ῂ㠦㍲⓪ 㞫ὧ ₆㑶㠦 㦮䟊 㠑 㠊㰚 Fig. 2 㦮 ἆὒ⪲䎆 ṗṗ㦮 ㌂㰚㠦 䟊╏♮
⓪ ‶㡊 ₎㧊㢖 Ṗ 䞮㭧㦚 ☯㔲㠦 䁷㩫䞶 㑮 㧞㠞₆ ➢ⶎ㠦 Ṗ⓻䞮㡖┺[7~14]. 㯟, 㔲䘎 䙃㠦
╖䞲 ‶㡊 ₎㧊㦮 ゚㥾 ⼖䢪㠦 ➆⧒ ╂⧒㰖⓪ 㦧
⩻ 䢫╖ Ἒ㑮Ṩ㦚 ṗ 䕢ᾊ ┾Ἒ㠦 ╖䞮㡂 㩫䢫䞮 Ợ ㌆㿲 Ṗ⓻䞮㡖₆ ➢ⶎ㧊Ⳇ, Fig. 3 㦮 䢪㌗ 㻮Ⰲ
₆⻫㧊 Ṗ⹎♲ ἆὒ⧒ 䞶 㑮 㧞┺. 䞲Ṗ㰖 㭒⳿䞶 㩦㦖, ⽎ 㔺䠮㠦㍲ 䁷㩫♲ 䘟‶ ‶㡊 㩚㰚 ㏣☚⓪
╖⨋ 㑮㕃 m/sec. 㑮㭖㦒⪲ ぢⰂ㰫 㦧⩻ 䁷㩫㦚 㥚䟊 㑮䟟♲ 䕢ᾊ 㔲䠮㠦 ゚䟊 ⰺ㤆 ザ⯎ 㭖-☯㩗 䕢ᾊ 㡗㡃㠦 䙂䞾♾㦚 㞢 㑮 㧞┺. ⁎⩂⋮ ⽎ 㡆 ῂ㠦㍲⓪ 㧊⩂䞲 㩚䕢 ㏣☚Ṗ ☯㩗 䕢ᾊ₢㰖 㯳 Ṗ♲ ộ㦖 㞚┞⸖⪲, K Ṩ 䁷㩫㠦 㧞㠊 ☯㩗 䣾ὒ
⯒ 䙂䞾㔲䅲 Ἒ㌆ 䞮㰖⓪ 㞠㞮┺. ἆὒ㩗㦒⪲ Fig.
5 ⓪ 㔺 ῂ㫆ⶒ㠦㍲ 䐋㌗㩗㦒⪲ ㌳♮⓪ 㭖-☯㩗
㌗䌲㠦㍲㦮 㧧㓺⩂㤊 䕢ᾊ 䡚㌗㦚 ⻢䋂 ゚㩫㰞 䞿⁞㠦㍲ 㰗㩧㩗㦒⪲ 䁷㩫䞲 㦮⹎㧞⓪ ἆὒ⧒ 䞶 㑮 㧞┺
71# ✾☧#
⽎ 㡆ῂ㠦㍲⓪ 㞫ὧ 䗮㧎䔎⯒ 㧊㣿䞮㡂 5%⌊
ZW_
GV穢剳暒昷儆击穟箒滆V洢YW劒G 洢[笾SGYWXX噊G G㣎㦮 ἆ㩫㌗㦚 䙂䞾䞮ἶ 㧞⓪ Zr41.2Ti13.8Cu12.5 Ni10.0Be22.5 ⻢䋂 ゚㩫㰞 ⁞㏣ 㨂⬢㦮 㧧㓺⩂㤊
‶㡊 㩚䕢 䡚㌗㦚 㔲ṗ㩗㦒⪲ Ỗ㿲䞮⓪ ㌞⪲㤊
₆⻫㦚 ☚㧛䞮㡖㦒Ⳇ, ☯ ₆㑶㦚 㧊㣿䞮㡂 䁷㩫♲
ἶ㏣㦒⪲ 㰚䟟♮⓪ ‶㡊 㡗䟻 䕢ᾊ Ệ☯㦖 ┺ 㦢ὒ ṯ㧊 㣪㟓♶ 㑮 㧞┺.
㤆㍶, 䕢ᾊ㦮 㩚⓪ 1~2Ṳ㦮 㩚┾ ⺊✲㠦 㰧 㭧♮㠊 ㌳♮Ⳇ, 㧊⪲ 㧎䟊 ㌳♲ 㡊㦖 䕢ᾊ㔲
゚㩫㰞 䞿⁞㧊 ὒ⌟ṗ 㞷㼊 㡗㡃㡾☚ 㧊㌗㦒⪲
㰚㧛䅖 䞾㦒⪲㖾 ‶㡊 㻾┾㠦㍲ 㣿㦋♲ 䡫䌲㦮 䕢Ⳋ㧊 ㌳㎇♮Ⳇ, ⁎ ἆὒ ở⽊₆ 䕢ᾊ 㧎㎇㦚
‶㡊 㩚㰚㠦 ➆⧒ ỿ䧞 㩖䞮㔲䋾 ộ㦒⪲ 䕦┾
♲┺.
Ⳋ, 䕢ᾊ㦮 䤚⓪ ‶㡊 㩚㰚㠦 ➆⯎ 㨂⬢
㦮 䌚㎇ 㿫㩗㠦⍞㰖 Ṧ㏢⪲ 㧎䞲 㡊⨟㦮 Ṧ㏢
Ṗ ⏨㦖 㣿㦋㡾☚⯒ Ṗ㰖⓪ ἆ㩫㌗✺㦮 㡃䞶㦚
ṗ 㔲䌊㦒⪲㖾 ‶㡊 㻾┾㠦㍲㦮 ┺㭧 㩚┾ ⺊
✲㦮 ㌳ ❇㦮 ‶㡊 ⚪䢪 㩚┾⺊✲ ぢ⧲䃃 䡚㌗㦚 㥶䞮Ⳇ, ⁎ ἆὒ ỿ䧞 Ṧ㏢♲ ☯ 㨂⬢
㦮 㦧⩻䢫╖ Ἒ㑮 Ṩ㧊 䐋㌗㩗㧎 㑮㭖㦒⪲ 䣢⽋
♲ ộ㦒⪲ 㿪㩫♲┺.
㝮 G
㧊 ⏒ⶎ㦖 2010⎚☚ ἓ╖䞯ᾦ 䞯㑶㡆ῂ゚(䔏
⼚㡆ῂ⽊㫆⁞ 㰖㤦)㠦 㦮䞮㡂 㡆ῂ♮㠞㦒⸖⪲ 㧊 㠦 Ṧ㌂ ✲Ⱃ┞┺.
Ⳣ ඊ ᯢ 㙶
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