Development of novel Zr-based MG for thermo-plastic forming

Development of novel Zr-based MG for thermo-plastic forming 구조재료심화연구 (Current Status of Structural Materials) March 20th, 2016 Kyung-jun Kim 1. Introduction: Thermoplastic forming of metallic glass 2. Alloy design 1) Binary Zr-TM MG for low T g 2) Ternary Zr-TM -TM MG for optimized thermal properties 3. Future work & Summary

1. Introduction: Thermo-plastic forming of metallic glass

Introduction of Metallic Glass Atomic structure of crystalline and amorphous materials Crystalline materials Amorphous materials Unlike crystalline materials, absence of long-range period Unique mechanical properties, corrosion resistance induced by no defect, homogeneous distribution

Introduction of Metallic Glass 2500 Strength vs. Elastic limit for several classes for materials 2000 Steels Strength (MPa) 1500 1000 Titanium alloys Metallic glass 500 Silica Woods Polymers 0 1 2 3 Elastic Limit (%) Metallic glass: High strength ( > 1.5GPa) + Large elastic limit ( ~2% )

Characteristic Temperature of Metallic Glass Representative DSC curve of metallic glasses the temperature regions sectioned according to phase transformations

High Formability of Metallic Glass According to Temperature G. Kumar et al., Nature, 457, 2009, 868-872 Temperature-dependent strength of materials Ideal processing region Comparison of strength change depending on temperature for various materials NC-Ni, PM M A(Poly M ethyl M ethacrylate), Au-BMG, Pt-BM G, Zr-BM G

Thermo-plastic Forming Process G. Kumar et al., Nature, 457, 2009, 868-872 Time-Temperature-Transformation diagram 1. 2. Path 1) Rapid cooling process: direct casting from liquid phase into the glassy state Path 2) Reheating process: under viscous flow condition, thermo-plastic forming in SCLR, ΔT x (=T g - T x )

High Formability of Metallic Glass Seamaster Planet Ocean Liquidmetal Limited Edition Outstanding Thermo-plastic Formability 1. Low processing temp. T g ~0.4T m 2. Sim ple form ing Com plex structure

High Formability of Metallic Glass G. Kumar et al., Nature, 457, 2009, 868-872 OM and SEM image of thermo-plastic formed Pt-BMG parts, rods M icro-forming of Pt -BMG fabricated by hot embossing on an etched Si wafer and hot cutting Nano-rod of Pt -BMG formed by embossing on porous alumina Fine & Precise formability

Consideration of Base Metal Candidate Glass transition temperature, fracture strength of various BMG and its record size(gfa) of various BM G 1000 6 Glass transition Temperature (Tg) 800 600 400 200 0 Fe-based BMG Ni-based BMG Ti-based BMG Cu-based BMG Zr-based BMG Al-based MG Mg-based BMG Ca-based BMG 0 50 100 150 200 250 300 Elastic modulus (GPa) 5 4 3 2 1 0 Fracture Strength (GPa) Base metal candidate: Zirconium M echanical properties, GFA (ex. critical diam eter, D c, ~70mm), Super-cooled liquid region (ex. ΔT x ~100K) cf) Al-based MG: Low GFA (only ribbon-shaped), Small super-cooled region (ΔT x ~20K), Mg-based M G: Brittle fracture Limitation: High processing temp., T g ~ 400 (cf. processing Temp. of polymer ~ 250 )

Research M otivation Zr-Cu binary phase diagram DSC analysis of Zr-Cu ribbon alloys Glass-forming region Zr 30 at.% ~ 70 at.% Exo. Heat Flow (a.u.) Cu 30 Zr 70 Cu 40 Zr 60 Cu 50 Zr 50 Cu 60 Zr 40 Cu 70 Zr 30 674K 623K 688K 649K 727K 684K 796K 753K 783K Heating rate: 40K/min as-spun Zr-Cu ribbon alloys 400 500 600 700 800 Temperature (K) Zr-rich glass-forming boundary composition, Zr 70 Cu 30 the low est T g, 623K (350 ) and large ΔT x, 51K

T g and T x Change Depending on Zr Content in Zr-Cu Binary System Glass transition temperature, Tg [K] 900 850 800 750 700 650 600 550 Tx of Zr-Cu binary system Tg of Zr-Cu binary system Boundary composition of glass-forming region in Zr-Cu binary system Prediction for low T g induced by Zr contents ΔT=51 K 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 Zr concentration [at.%] Decrease of Tg depending on Zr content Develop novel Zr-rich Zr-TM glassy alloy system for low T g

2-1) Alloy design, Binary Zr-TM M G for low Tg

Limitation of Alloy Design for Zr-rich Binary MG Consideration of glass formation

Limitation of Alloy Design for Zr-rich Binary MG E.S. Park et al., J. Appl. Phys., 118, 2015, 064902 Schematic continuous-cooling-transformation (CCT) diagram, representing the characteristics temp.

Retention of Liquid Phase Ni-Zr 이원합금시스템의평형상태도 Co-Zr 이원합금시스템의평형상태도 Zr 76at.% 조성에서 Eutectic 조성존재 Zr 78.5at.% 조성에서 Eutectic 조성존재 낮은온도에서도액상이안정하게유지되는 eutectic 조성의경우, 비정질형성능이높다고보고됨. Zr계이원합금시스템중 Zr 70at.% 이상에서비정질형성이가능할것으로판단되는이원합금시스템을조사. Ni-Zr 이원합금시스템에서는 Zr 조성기준 76at.%, Co-Zr 이원합금시스템에서는 Zr 조성기준 78.5at% 의높은 Zr-rich 조성에서 eutectic 조성을형성, 비정질형성가능성이확인.

Thermodynamical and Structural Point ΔH mix <<0 Zr TM A. Takeuchi et al., Materials Transactions, 46, 12, 2005, 2817-2829 Atomic radius [Å] Atomic radius difference [%] ΔH mix [kj/mol] Zr 1.62 Cu 1.28 21.0-23 Ni 1.25 22.8-49 Co 1.25 22.8-41 비정질합금형성에관한경험법칙에의해원자반경과열역학적관계를고려. Zr-Ni 및 Zr-Co 이원합금시스템 : 1) Zr 과의원자반경차이도크며 (22.8%), 2) 혼합열도음의관계로큼.

Zr-Ni Binary Ribbon Alloys Zr-Ni 이성분합금계실험조성 해당조성영역에서리본시편제작 비정질형성능및열특성평가 Zr-Ni 리본합금의 XRD 분석 as-spun Zr-Ni ribbon alloys Zr 70 Ni 30 only diffuse halo peak Intensity (a.u.) Zr 72 Ni 28 Zr 74 Ni 26 Zr 76 Ni 24 Zr 78 Ni 22 20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (deg.) 제조된 Zr-rich Ni-Zr 리본합금의 GFA 확보 Zr-Ni 이원합금시스템내 Zr 조성기준 76 at.% 에위치한 eutectic 조성부근에실험조성을선정. 이조성영역에서 Arc melting 으로모합금을제조, RSP 를통해리본시편 (0.03 (t) X 2.5mm (W)) 을제조. 제작된리본시편의 XRD 상분석을실시, 비정질형성능을평가.

Zr-Ni Binary Ribbon Alloys Exo. Heat Flow (a.u.) Zr 70 Ni 30 Zr 72 Ni 28 Zr 74 Ni 26 Zr 76 Ni 24 Zr 78 Ni 22 Heating rate: 40K/min Zr-Ni 리본합금의 DSC 분석 650K 653K 636K 620K 615K 594K 591K 636K 400 500 600 700 800 Temperature (K) as-spun Zr-Ni ribbon alloys Supercooled liquid region, ΔTx [K] Characteristic temperature, Tg, Tx [K] 680 660 640 620 600 580 40 30 20 10 DSC 분석을통한, 특성화온도 Plot 650 653 636 636 620 17 16 0 68 69 70 71 72 73 74 75 76 77 78 79 80 Zr concentration (at.%) 제조된 Zr-rich Ni-Zr 리본합금의최저 T g 조성확인 Zr 76 Ni 24 조성은비정질상형성과최저 T g 를가짐. 615 594 21 591 Zr-Cu 이원합금시스템과유사하게 Zr-Ni 이원합금시스템에서도 Zr 함량에따라 T g 가감소함을확인. 최저 T g 는 Zr 76 Ni 24 합금에서 594K (321 ) 로 Cu-Zr 이원합금시스템의최저 T g 와비교, 약 30 K 가량낮아짐. 단, ΔT x 가 21 K 으로목표대비 30 K 정도좁으므로, ΔT x 를넓히도록추가적인합금설계가필요함.

Zr-Co Binary Ribbon Alloys Zr-Co 이성분합금계실험조성 해당조성영역에서리본시편제작 비정질형성능및열특성평가 Zr-Co 리본합금의 XRD 분석 as-spun Zr-Co ribbon alloys Zr 77 Co 23 only diffuse halo peak Zr 78 Co 22 Intensity (a.u.) Zr 78.5 Co 21.5 Zr 79 Co 21 Zr 80 Co 20 Zr 81 Co 19 20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (deg.) 제조된 Zr-rich Co-Zr 리본합금의 GFA 확보 Zr-Co 이원합금시스템내 Zr 조성기준 78.5at.% 에위치한 eutectic 조성부근에실험조성을선정. 이조성영역에서 Arc melting 으로모합금을제조, RSP 를통해리본시편 (0.03 (t) X 2.5mm (W)) 을제조. 제작된리본시편의 XRD 상분석을실시, 비정질형성능을평가.

Zr-Co Binary Ribbon Alloys Exo. Heat Flow (a.u.) Zr 77 Co 23 Zr 78 Co 22 Zr 78.5 Co 21.5 Zr 79 Co 21 Zr 80 Co 20 Zr 81 Co 19 Heating rate: 40K/min Zr-Co 리본합금의 DSC 분석 611K 590K 584K 566K 663K 637K 643K 620K 628K 607K 400 500 600 700 800 Temperature (K) as-spun Zr-Co ribbon alloys Supercooled liquid region, ΔTx [K] Characteristic temperature, Tg, Tx [K] 680 660 640 620 600 580 560 40 30 20 10 DSC 분석을통한, 특성화온도 Plot 663 637 26 643 620 23 628 607 611 590 21 21 0 76 77 78 79 80 81 82 Zr concentration (at.%) 제조된 Zr-rich Co-Zr 리본합금의최저 T g 조성확인 Zr 79 Co 21 조성은비정질상형성과최저 T g 를가짐. 584 566 Zr-Co 이원합금시스템역시 1 at.% 의크지않은조성변화에도불구하고, Zr 함량에따라 T g 가감소함을확인. 최저 T g 는 Zr 79 Co 24 합금에서 590K (317 ) 로 Cu-Zr 이원합금시스템의최저 T g 와비교, 약 33K 가량낮아짐. Zr-Ni 과마찬가지로 ΔT x 가 21K 으로목표대비 30K 정도좁으므로, ΔT x 를넓히도록추가적인합금설계가필요함.

Characteristic Temperature of Zr-TM (=Cu, Ni, Co) Binary Metallic Glass Glass transition temperature [K] 900 850 800 750 700 650 600 550 Target T g, 573K (300 ) < T g < 593K (320 ) T g =623K ΔT=51K 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 Zr concentration [at.%] Tx of Zr-Cu binary system Tg of Zr-Cu binary system Tx of Zr-Ni binary system Tg of Zr-Ni binary system Tx of Zr-Co binary system Tg of Zr-Co binary system T g =594K ΔT=21K T g =590K ΔT=21K Zr-rich Zr-TM 이원합금시스템개발로 T g 를 30K (Zr 70 Cu 30, T g =623K Zr 79 Co 21, T g =590K) 이상감소시킴. 단, 이두합금시스템에서개발된합금의경우열성형가능구간인 ΔT x 가 20K 내외로좁음. ( 목표 > 50K) 양산에적합한열특성효율확보를위해, T g 를더욱낮추면서, ΔT x 는넓힐수있는추가적인합금설계필요.

Characteristic Temperature of Zr-TM (=Cu, Ni, Co) Binary MG 660 650 Cu-Zr binary system Ni-Zr binary system Co-Zr binary system Glass transition tempearture, Tg [K] 640 630 620 610 600 590 580 570 2. Zr 76 Ni 24, Zr 79 Co 21 binary alloys 1) T g : 594K, 590K 2) ΔT x : 21K alloy design 2] keep T g, increase ΔT x ΔT x > 50K 1. Zr 70 Cu 30 binary alloys 1) T g : 623K 2) ΔT x : 50K alloy design 1] keep ΔT x, lower T g Ideal processing temp. region 573K < T g < 593K 560 10 15 20 25 30 35 40 45 50 55 60 65 70 Super-cooled liquid region, ΔTx [K]

Summary of Zr-TM (=Cu, Ni, Co) Binary Metallic Glass Zr-Cu alloy system Zr-Ni alloy system Zr-Co alloy system the lowest T g Cu 30 Zr 70 T g = 623K, (~30K over) ΔT x = 51K the lowest T g Ni 24 Zr 76 T g = 594K ΔT x = 21K, (~29K under) the lowest T g Co 21 Zr 79 T g = 590K ΔT x = 21K, (~29K under) Zr-Cu-TM (TM=Ni, Co) alloy system Large ΔT x, Zr-Cu binary system + low T g, Zr-TM binary system Zr-Cu-TM ternary alloy system Alloy design keep T g, increase ΔT x

2-2) Alloy design, Ternary Zr-TM -TM MG for optimized thermal properties

Alloy Design for Ternary MG Composition? H. Bo et al., Intermetallics, 18, 2010, 2322-2327 1] ΔT x 는넓지만, T g 가높아공정조건에제한이있는 Zr-Cu 이원합금시스템 2] T g 가매우낮지만반대로 ΔT x 가좁아열성형구간에제한이존재하는 Zr-Ni 및 Zr-Co 이원합금시스템 Zr-Cu-TM (TM= Ni, Co) 로의합금설계를통해높은열성형온도및좁은열성형구간을동시에극복할수있을것이라판단.

Ternary Phase Diagram Prediction for Zr-Cu-TM (=Ni, Co) Predicted by using Thermo-Calc. with SSOL6 database Zr-Cu-Ni 삼원합금시스템의평형상태도 Zr 0.00 1.00 Zr-Cu-Co 삼원합금시스템의평형상태도 Zr 0.00 1.00 0.05 0.95 0.05 0.95 0.10 0.90 0.10 0.90 0.15 0.85 0.15 0.85 0.20 0.80 0.20 0.80 0.25 0.75 0.25 0.75 0.30 Zr-rich Ternary eutectic comp. 0.70 0.30 Zr-rich Ternary eutectic comp. 0.70 0.35 0.65 0.35 0.65 0.40 0.60 0.40 0.60 0.45 0.55 0.45 0.55 0.50 0.50 Cu Ni 0.50 0.50 Cu Co Thermo-Calc 프로그램을통해낮은온도에서도액상의안정성이높은 ternary eutectic 조성영역및 liquidus line 을계산 비정질형성능이높을것으로예측되는조성군을확인하고, 실험조성을설계

Alloy Design for Zr-rich Zr-Cu-Ni Ternary M G Predicted by using Thermo-Calc. with SSOL6 database 0.00 Zr 1.00 0.05 0.95 0.10 0.90 0.15 0.85 0.20 Zr-rich Ternary eutectic comp. 0.80 Zr 76 Ni 24 0.25 Zr 72.4 Cu 18 Ni 9.6 0.75 Zr 70 Cu 30 0.30 Zr 71.2 Cu 24 Ni 4.8 Zr 73.6 Cu 12 Ni 14.4 Zr 74.8Cu 6 Ni 19.2 0.70 0.35 0.65 0.40 0.60 Cu (Zr 70 Cu 30 ) x (Zr 76 Ni 24 ) 1-x, x = 0.2, 0.4, 0.6, 0.8 Zr-Cu-Ni 삼원평형상태도에대해 Thermo-Calc를통해계산된 ternary eutectic 조성및 liquidus line과가장낮은유리천이온도를보였던두조성인 (Zr 70 Cu 30 )-(Zr 76 Ni 24 ) 를이은 line이서로유사함을확인. (Zr 70 Cu 30 ) x (Zr 76 Ni 24 ) 1-x 를실험조성으로설계하여, 비정질형성능및열특성변화를관찰 Ni

Experimental Result of Zr-rich Zr-Cu-Ni Ternary M G Exo. Heat Flow (a.u.) Zr 76 Ni 24 Zr 74.8 Cu 6 Ni 19.2 609K Zr 73.6 Cu 12 Ni 14.4 641K 608K Zr 72.4 Cu 18 Ni 9.6 637K 605K Zr 71.2 Cu 24 Ni 4.8 657K 610K Zr 70 Cu 30 Heating rate: 40K/min 629K as-spun (Zr 70 Cu 30 ) x (Zr 76 Ni 24 ) 1-x ribbon alloys 400 500 600 700 800 1. 비정질형성능 615K 594K 623K Temperature (K) 674K ΔH = -65.65 J/g ΔH = -68.70 J/g ΔH = -69.65 J/g ΔH = -74.65 J/g ΔH = -82.98 J/g ΔH = -81.10 J/g Characteristic temperature, Tg, Tx [K] 690 680 670 660 650 640 630 620 610 600 590 580 570 674 51 623 657 47 610 637 32 605 641 33 608 629 609 20 Tx Tg 615 594 Zr70Cu30 x = 0.8 x = 0.6 x = 0.4 x = 0.2 Zr76Ni24 Low Zr at.% / Cu-rich ΔTx 21 High Zr at.% / Ni-rich (Zr 70 Cu 30 ) x (Zr 76 Ni 24 ) 1-x, x=0.2, 0.4, 0.6, 0.8 조성모두 XRD 상으로 diffuse halo peak 의 amorphous phase 만관찰 2. 조성에따른열특성변화 High Zr at.% / Ni-rich Low Zr at.% / Cu-rich x=0.2, 0.4, 0.6, 0.8 조성모두 T g 는 605~610K 전후로비슷한수준이나, Cu-rich 조성에서 ΔT x 가 45K 이상으로형성됨. Cu 와 Ni 간치환함으로써비정질형성능을높이고, Zr-rich 영역에서비정질을형성시킴으로써 T g 를더낮출수있었음. 또한넓은 45K 이상의 ΔT x 를가지는 Cu-rich 조성은 glassy phase 의 stability 가우수해 Zr-rich 으로조성조절이가능함을의미 80 70 60 50 40 30 20 10 Supercooled liquid region, ΔTx [K]

Alloy Design for Zr-rich Zr-Cu-Co Ternary M G Predicted by using Thermo-Calc. with SSOL6 database 0.00 Zr 1.00 0.05 0.95 0.10 0.90 0.15 0.85 0.20 Zr-rich Ternary eutectic comp. Zr 77.2 Cu 6 Co 16.8 0.80 0.25 Zr 73.6 Cu 18 Co 8.4 Zr 79 Co 21 0.75 Zr 70 Cu 30 0.30 Zr 71.8 Cu 24 Co 4.2 Zr 75.4 Cu 12 Co 12.6 0.70 0.35 0.65 0.40 0.60 Cu (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x, x = 0.2, 0.4, 0.6, 0.8 Thermo-Calc를통해계산된 Zr-rich Zr-Cu-Co ternary eutectic 조성및 liquidus line과가장낮은유리천이온도를보였던두조성인 (Zr 70 Cu 30 )-(Zr 79 Co 21 ) 를이은 line이서로유사함을확인. (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x 를실험조성으로설계하여, 비정질형성능및열특성변화를관찰 Co

Experimental Result of Zr-rich Zr-Cu-Co Ternary M G Exo. Heat Flow (a.u.) Zr 79 Co 21 Zr 77.2 Cu 6 Co 16.8 Zr 75.4 Cu 12 Co 12.6 Zr 73.6 Cu 18 Co 8.4 Zr 71.8 Cu 24 Co 4.2 Zr 70 Cu 30 Heating rate: 40K/min 611K 590K 636K 615K 623K 602K 643K 609K 618K 623K 666K as-spun (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x ribbon alloys 400 500 600 700 800 1. 비정질형성능 Temperature (K) 674K High Zr at.% / Co-rich ΔH = -55.51 J/g ΔH = -52.02 J/g ΔH = -55.22 J/g ΔH = -76.59 J/g ΔH = -73.30 J/g ΔH = -81.10 J/g Low Zr at.% / Cu-rich Characteristic temperature, Tg, Tx [K] 690 680 670 660 650 640 630 620 610 600 590 580 570 674 51 623 666 48 618 643 34 609 623 602 21 636 615 21 Tx Tg 611 590 Zr70Cu30 x = 0.8 x = 0.6 x = 0.4 x = 0.2 Zr79Co21 Low Zr at.% / Cu-rich ΔTx 21 High Zr at.% / Co-rich (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x, x=0.2, 0.4, 0.6, 0.8 조성모두 XRD 상으로 diffuse halo peak 의 amorphous phase 만관찰 2. 조성에따른열특성변화 (Zr 70 Cu 30 ):(Zr 79 Co 21 ) 비에따라열특성온도에변화가극심하고, Cu-rich 조성에서는 ΔT x 가 45K 이상으로형성됨. 80 70 60 50 40 30 20 10 Supercooled liquid region, ΔTx [K] Cu 와 Co 간치환함으로써비정질형성능을높이고, Zr-rich 영역에서비정질을형성시킴으로써 T g 를더낮출수있었음. 또한넓은 45K 이상의 ΔT x 를가지는 Cu-rich 조성은 glassy phase 의 stability 가우수해 Zr-rich 으로조성조절이가능함을의미

Additional Alloy Design for Zr-rich Zr-Cu-Co Ternary M G (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x, x=0.8 조성의 Cu:Co 비인 85:15 을고정, Zr 함량을증가시킨 Zr 100-x (Cu 85 Co 15 ) x 조성설계 0.00 Zr 1.00 as-spun Zr 100-x (Cu 85 Co 15 ) x ribbon alloys 0.05 0.95 Zr 71.8 Cu 24 Co 4.2 0.10 0.90 Intensity (a.u.) Zr 72 (Cu 85 Co 15 ) 28 Zr 74 (Cu 85 Co 15 ) 26 Zr 76 (Cu 85 Co 15 ) 24 Zr 78 (Cu 85 Co 15 ) 22 0.15 0.20 Zr 78 Cu 18.7 Co 3.3 Zr 76 Cu 20.4 Co 3.6 0.25 Zr 74 Cu 22.1 Co 3.9 0.85 0.80 Zr-rich Ternary eutectic comp. 0.75 20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (deg.) 0.30 Zr 71.8 Cu 24 Co 4.2 Zr 72 Cu 23.8 Co 4.2 0.70 0.35 0.65 0.40 0.60 1. 비정질형성능 Zr 74 조성까지는 amorphous phase만관찰됨. Zr 76 조성부터 XRD 상으로 crystalline phase가관찰됨. Cu Co

Experimental Result of Zr-rich Zr-Cu-Co Ternary M G Exo. Heat Flow (a.u.) Zr 71.8 Cu 24 Co 4.2 666K ΔH = -73.30 J/g 618K Zr 72 (Cu 85 Co 15 ) 28 650K ΔH = -83.66 J/g 606K Zr 74 (Cu 85 Co 15 ) 26 612K 592K ΔH = -75.79 J/g Zr 76 (Cu 85 Co 15 ) 24 596K 577K ΔH = -68.06 J/g Heating rate: 40K/min as-spun Zr 100-x (Cu 85 Co 15 ) x ribbon alloys 400 500 600 700 800 Temperature (K) Zr-enrich Characteristic temperature, Tg, Tx [K] 690 680 670 660 650 640 630 620 610 600 590 580 570 666 48 618 650 44 612 606 596 592 19 20 577 Zr71.8Cu24Co4.2 Zr72 Zr74 Zr76 High Zr at.% Tx Tg ΔTx 80 70 60 50 40 30 20 10 Supercooled liquid region, ΔTx [K] 2. 조성에따른열특성변화 Zr 72 조성은 Zr 이단 0.2at% 감소했음에도 T g 가 10K 이상크게감소하면서 ΔT x 는 44K 로비슷한수준을유지함 이후 Zr 증가에따라 T g 도감소하나, T x 의감소폭이더커, T g 가 592K 및 577K 로 Zr 74, Zr 76 조성부터 ΔT x 가급격히감소

DSC curve analysis of Zr-TM binary alloys Zr-Ni binary system phase diagram Zr-Co binary system phase diagram Eutectic Comp. Zr 76at.% Eutectic Comp. Zr 78.5at.% β-zr peak on X-ray diffraction pattern Separation Glassy phase β-zr crystalline phase reaction?

DSC curve analysis of Zr-Cu-TM ternary alloys 1. DSC curve analysis of large ΔT x comp. relatively low Zr content Cu-rich region wide & flat 한 plateau of super-cooled liquid region Sharp & deep crystallization peak 2. DSC curve analysis of low T g comp. relatively high Zr content Ni-rich or Co-rich region Crystallization peak separation Crystallization peak broadening

Schematic T-T-T diagram of Zr-rich alloys Change of T g and C-curve of schematic T-T-T diagram depending on Zr contents Liquid phase T l Cooling C-curve of β-zr shift Zr-enrich Crystalline phase Heating T x Zr-enrich Super-cooled liquid region Glass T g T x T g Contradiction of Zr-enrich alloy design T g decrease but, GFA and ΔT x decrease more To develop of Low T g Zr-rich metallic glass, Controlling decrease of ΔT x induced by crystallization reaction behavior change

Effect of Al small addition in (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x Crystallization peak separation comp. (Zr 70 Cu 30 ) x (Zr 79 Co 21 ) 1-x line and DSC curve disturb peak separation through small addition of Al, 1, 3 at.% Plateau of super-cooled liquid region and crystallization peak becomes clear and sharp

Characteristic temperature evaluation of Zr-Cu-TM (=Ni, Co) Ternary MG Glass transition tempearture, Tg [K] 660 650 640 630 620 610 600 590 580 570 Zr 74 Cu 22.1 Co 3.9 Zr 75.4 Cu 12 Co 12.6 Zr 76 Ni 24 Zr 79 Co 21 Zr 72.4 Cu 18 Ni 9.6 Zr 73.6 Cu 18 Co 8.4 (Zr 73.6 Cu 12 Ni 14.4 ) 97 Al 3 Zr 73.6 Cu 12 Ni 14.4 (Zr 73.6Cu 12Ni 14.4) 99Al 1 (Zr 73.6 Cu 18 Co 8.4 ) 97 Al 3 How to break through? Zr 71.8 Cu 24 Co 4.2 Zr 70 Cu 30 Zr-Cu binary system Zr-Ni binary system Zr-Co binary system Zr-Cu-Ni ternary system Zr-Cu-Co ternary system ΔT x > 50K Ideal processing temp. region 573K < T g < 593K 560 10 15 20 25 30 35 40 45 50 55 60 65 70 Super-cooled liquid region, ΔTx [K]

3. Future work and Summary: Additional alloy design

New Alloy Design of Zr-Ti-Cu-Ni quaternary system M. Seidel et al., Materials Letters, 23, 1995, 299-304

New Alloy Design of Zr-Ti-Cu-Ni quaternary system D. Ma, et al., Physical Review Letters, 108, 2012, 085501 nano-scale supercluster (MRO) solute-centered clusters (SRO) Local packing of solvent atoms Substitution of Zr-Zr weak bonding by Ti addition

Characteristic temperature of Zr-TM (=Cu, Ni, Co) binary metallic glass Intensity (a.u.) as-spun ZrTiCuNi ribbon alloys Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 Zr 65 Ti 7.5 Cu 17.5 Ni 10 Zr 63.33 Ti 8.89 Cu 15.45 Ni 12.33 Exo. Heat Flow (a.u.) Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 621K 579K Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 598K 557K Zr 65 Ti 7.5 Cu 17.5 Ni 10 622K 597K Zr 63.33 Ti 8.89 Cu 15.45 Ni 12. 624K 33 597K Zr 65 Ti 10 (Cu 20 Ni 10 Al 5 ) 2 629K 5 594K ΔH = -66.57 J/g ΔH = -63.35 J/g ΔH = -62.38 J/g ΔH = -59.61 J/g ΔH = -63.44 J/g Zr 65 Ti 10 (Cu 20 Ni 10 Al 5 ) 2 5 20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (deg.) Heating rate: 40K/min as-spun ZrTiCuNi ribbon alloys 400 500 600 700 800 Temperature (K) as-spun (ZrTiCuNi) 100-x Al x ribbon alloys Intensity (a.u.) (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 99 Al 1 (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 97 Al 3 (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 99 Al 1 Exo. Heat Flow (a.u.) (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 99 Al 1 629K 584K (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 97 Al 3 644K 594K (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 99 Al 1 612K 568K (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 97 Al 3 619K 578K ΔH = -49.39 J/g ΔH = -43.57 J/g ΔH = -63.13 J/g ΔH = -59.40 J/g (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 97 Al 3 20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (deg.) Heating rate: 40K/min as-spun (ZrTiCuNi) 100-x Al x ribbon alloys 400 500 600 700 800 Temperature (K)

Characteristic temperature of Zr-TM (=Cu, Ni, Co) binary metallic glass Glass transition tempearture, Tg [K] 660 650 640 630 620 610 600 590 580 570 Zr 74 Cu 22.1 Co 3.9 Zr 76 Ni 24 Zr 79 Co 21 Zr 72.4 Cu 18 Ni 9.6 Zr 73.6 Cu 18 Co 8.4 (Zr 73.6 Cu 12 Ni 14.4 ) 97 Al 3 Zr 73.6 Cu 12 Ni 14.4 (Zr 73.6Cu 12Ni 14.4) 99Al 1 (Zr 73.6 Cu 18 Co 8.4 ) 97 Al 3 Zr 71.8 Cu 24 Co 4.2 Zr 75.4 Cu 12 Co 12.6 (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 97 Al 3 (Zr 58.7 Ti 13.8 Cu 17.5 Ni 10 ) 99 Al 1 (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 97 Al 3 Zr 58.7Ti 13.8Cu 17.5Ni 10 (Zr 63.7 Ti 13.8 Cu 12.5 Ni 10 ) 99 Al 1 Zr-Cu binary system Zr-Ni binary system Zr-Co binary system Zr-Cu-Ni ternary system Zr-Cu-Co ternary system Zr-Cu-Ni-Al quaternary system Zr-Ti-Cu-Ni quaternary system Zr-Ti-Cu-Ni-Al quinary system 560 10 15 20 25 30 35 40 45 50 55 60 65 70 Zr 70 Cu 30 Super-cooled liquid region, ΔTx [K] ΔT x > 50K Ideal processing temp. region 573K < T g < 593K

Summary 현재연구진행사항 Zr-Cu-TM (TM=Ni, Co) alloy system 개발 Zr-Cu 합금계와 Zr-TM 합금계를참고하여 Zr-Cu-TM 삼원합금시스템개발 두합금계의열특성장점이융합된합금개발 T g 는낮추고, ΔT x 는증가시킨합금개발 결정화거동분석 Zr-rich 조성의이원계및삼원계비정질합금 DSC 결과와조성및 XRD 분석비교 조성에따른결정화거동분석 실험조성및열특성데이터베이스화 (Zr-Cu-Ni), (Zr-Cu-Co) 삼원합금계의비정질합금형성영역및결정화거동변화경계조성조사 조성및열특성데이터베이스를작성하여, 사원, 오원합금시스템개발을위한기반확립 결정화거동제어가가능한소량첨가원소조사 Low T g 를위해 Zr-rich 조성개발 GFA 감소와 ΔT x 감소가불가피함 Al 조성최적화및이외소량첨가원소검색을통해 Zr-rich 조성개발의한계점을 Break through < 궁극적인목표 > 우수한열성형능을가지는비정질신합금개발및기계적특성, 산화저항평가

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