lass forming ability of binary ZR CU and ternary ZR CU AL alloys

GLASS FORMING ABILITY OF BINARY ZR-CU AND TERNARY ZR-CU-AL ALLOYS WANG DONG (M.Eng, HUST) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF MATERIALS SCIENCE & ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2008 Acknowledgments I would like to express my sincere appreciation and thanks to my supervisor, Associate Professor Li Yi., for his supervision, constructive advice and help throughout this project. Special thanks to the technicians in Department of Materials Science and Engineering, Mr. Chan Yew Weng, Mr. Chen Qun, Ms. Lim Agnes, and Ms. Yin Hong for helping me make use of the Laboratory’s equipment. To the members of the non-equilibrium processing Lab, past and present, I extend my very sincere thanks. Their friendship and help during my study have been wonderful. It is the opportunity to have met and worked with all of them that has made my studies worthwhile. Words cannot express the gratitude and debt I owe to my parents. Without their encouragement and support I am sure I would not have had the strength to finish this project. Lastly, I would like to acknowledge the support of the National University of Singapore for granting me a research scholarship. 2008 Singapore Dong WANG i Table of Contents Acknowledgement i Table of Contents ii Summary vi List of Tables ix List of Figures x List of Publication xxiv Chapter Introduction Chapter Literature Review .5 2.1 Development and property of bulk metallic glasses . 2.1.1 Development of bulk metallic glasses . 2.1.2 Properties of bulk Metallic Glasses . 11 2.2 Practical methods of preparing bulk metallic glasses . 13 2.2.1 Water quenching 13 2.2.2 Casting method 14 (a) Chill casting method 14 (b) High-pressure die casting method . 14 (c) Suction casting method 16 2.2.3. Bridgman solidification technique 16 2.3 Scaling parameters for glass forming ability 17 2.3.1 Reduced glass transition temperature Trg . 18 2.3.2 Extent of undercooled liquid region ∆Tx 20 ii 2.3.3 Failure of GFA scaling parameters 21 2.4 Empirical rules to discover alloy systems forming BMGs . 21 2.4.1 Thermodynamics consideration . 22 2.4.2 Kinetics consideration 22 2.4.3 Structure consideration 23 2.5 Glass formation in Zr based alloys . 25 Chapter Experimental Procedure 29 3.1 Sample preparation . 29 3.1.1 Alloy preparation . 29 3.1.2 Chill casting . 29 (a) mm copper mould casting 29 (b) mm and mm copper mould casting . 31 3.2 Microstructure characterization 32 3.2.1 X-ray diffraction 32 3.2.2 Optical microscopy and scanning electron microscopy . 33 3.3 Thermal analysis . 34 3.3.1 Differential scanning calorimeter 34 3.3.2 Differential thermal analysis 35 Chapter Results 36 4.1 GFA study of alloys in Cu8Zr3-Cu10Zr7 binary eutectic system . 36 4.1.1 mm casting of alloys in Cu8Zr3-Cu10Zr7 eutectic system 37 4.2 Melting study of alloys in τ3-Zr2Cu-ZrCu, τ3-τ5-ZrCu and τ5-ZrCu-Cu10Zr7 ternary eutectic systems 45 4.2.1 Eutectic point in τ3-τ5-ZrCu system . 45 4.2.2 Eutectic points in τ5-ZrCu-Cu10Zr7 and τ3-Zr2Cu-ZrCu systems . 47 4.3 GFA study of alloys in τ3-τ5-ZrCu ternary eutectic system 49 4.3.1 mm casting of the eutectic alloy in τ3-τ5-ZrCu system . 49 4.3.2 Formation of (τ3 + glass matrix) composite . 50 4.3.3 Formation of (τ5 + glass matrix) composite . 57 4.3.4 Formation of (ZrCu + glass matrix) composite . 61 iii 4.3.5 Formation of mm fully amorphous BMG . 63 4.3.6 Formation of mm fully amorphous BMG . 70 4.4 GFA study of alloys in τ5-ZrCu-Cu10Zr7 ternary eutectic system 72 4.5 GFA study of alloys in τ3-Zr2Cu-ZrCu ternary eutectic system . 81 Chapter Discussions 92 5.1 Correlation between GFA and Trg, ∆Tx in binary Cu8Zr3-Cu10Zr7 system . 92 5.2 A new strategy to pinpoint the optimum glass former in binary eutectic systems . 95 5.2.1 Concept of phase selection . 95 5.2.2 Calculated optimum glass forming zone in Cu8Zr3-Cu10Zr7 system 98 5.2.3 Establishment of a new strategy to pinpoint the optimum glass former in binary eutectic systems . 105 5.2.4 Confirmation of the microstructure-based strategy for pinpointing the optimum glass former in binary eutectic by Cu8Zr3-Cu10Zr7 system . 109 5.2.5 Other Considerations . 113 (a) Strong dependency of GFA on alloy composition in binary alloy systems 113 (b) Binary BMGs 113 5.3 Correlation between GFA and Trg, ∆Tx in ternary τ3-τ5-ZrCu, τ5-ZrCu-Cu10Zr7 and τ3-Zr2Cu-ZrCu systems . 114 5.3.1 τ3-τ5-ZrCu system 117 5.3.2 τ5-ZrCu-Cu10Zr7 system . 120 5.3.3 τ3-Zr2Cu-ZrCu system . 121 5.4 A new strategy to pinpoint the optimum glass former in ternary eutectic systems . 123 5.4.1 Establishment of a new strategy to pinpoint the optimum glass former in ternary eutectic systems 123 5.4.2 Confirmation of the microstructure-based strategy for pinpointing the optimum glass former in ternary eutectic by τ3-τ5-ZrCu, τ5-ZrCu-Cu10Zr7 and τ3-Zr2Cu-ZrCu systems 131 (a) Previously reported Zr-Cu-Al bulk metallic glasses . 131 (b) τ3-τ5-ZrCu system . 132 iv (c) τ5-ZrCu-Cu10Zr7 system 134 (d) τ3-Zr2Cu-ZrCu system . 137 5.4.3 Other considerations 139 (a) Composite formation . 139 (b) Strong dependency of GFA on alloy composition in ternary alloy systems. 140 Chapter Conclusions .142 Chapter Future Work .144 Bibliography 146 Appendix 150 v Summary Although since the 1960s, many metallic glasses and bulk metallic glasses (BMGs) have been reported, the way to find the alloy composition with the optimum glass forming ability (GFA) within an alloy system still remains unclear. The first purpose of the present study is to establish a practical strategy to pinpoint the optimum glass forming alloy precisely in an alloy system. Zr based alloy systems have become one of the most promising to discover bulk metallic glasses. Moreover, Zr based bulk metallic glasses have exhibited a combination of various good mechanical properties, which cannot be obtained for conventional crystalline alloys. The second purpose of the present study is to obtain bulk metallic glasses in the Zr-Cu binary and the Zr-Cu-Al ternary systems. In this work, based on the principle of the competition of the formation/growth of glass and crystalline phases, a metallographic strategy to pinpoint the optimum glass former within a binary eutectic alloy system was established. The essence of this metallographic strategy is that by monitoring the microstructure evolution with composition and finding the junction where two composite (glass + primary phase α, glass + primary phase β) zones meet, one can precisely pinpoint the optimum glass former in the binary eutectic system. With the implementation of this strategy in the binary Cu8Zr3-Cu10Zr7 eutectic system, we successfully found the optimum glass forming vi alloy in this system and obtained mm Zr35.5Cu64.5 bulk metallic glass. This breaks the empirical condition previously believed necessary for BMG formation, i.e. a multicomponent recipe with at least three components. By extending the metallographic strategy for pinpointing the optimum glass former within a binary eutectic alloy system to ternary systems, a metallographic strategy to pinpoint the optimum glass former within a ternary eutectic alloy system was also established. This metallographic strategy was applied to three adjacent eutectic systems, τ3(Zr51Cu28Al21)-τ5(Zr38Cu36Al26)-ZrCu, τ5-ZrCu-Cu10Zr7 and τ3-Zr2Cu-ZrCu, and three optimum glass forming alloys (region) were precisely pinpointed. The discovered optimum glass forming alloy in the τ3-τ5-ZrCu eutectic system can even form mm bulk metallic glass. During the implementation of these metallographic strategies, we found that GFA has a strong dependency on the alloy composition in both binary and ternary eutectic systems. For example, in the binary Cu8Zr3-Cu10Zr7 eutectic system, only Cu64.5Zr35.5 can obtain mm fully glass cast rod; deviations of only 0.5 at% caused the appearance of crystalline in mm cast rods. Moreover, the mm BMG composite zone (encompassing the optimum glass forming composition, Cu64.5Zr35.5) was only from Cu63Zr37 to Cu65.5Zr34.5, a mere 2.5 at% range. In the τ3(Zr51Cu28Al21)-τ5(Zr38Cu36Al26)-ZrCu eutectic system, at% compositional deviation away from the optimum glass forming alloy, Zr48Cu45Al7, decreased the BMG size from mm to mm. This narrow bulk-glassforming range and strong composition dependency of GFA explains why our discovered binary bulk metallic glasses and ternary bulk metallic glasses were missed before. It also vii manifests the advantage of our microstructure-based strategies to pinpoint optimum glass formers. viii List of Tables Table 2.1 Summary of Bulk Metallic Glass Alloys with critical size bigger that 10 mm. (Adapted from Ref. [37]) Page Table 2.2 Summary of bulk metallic glass’s application and expected application in the future. (adapted from Ref. [10]) Page 12 Table 2.3 Typical Zr based ternary bulk metallic glasses. Page 27 Table 2.4 Properties of Vit1 BMGs compared with some crystalline metal alloys. (adapted from Ref. [11]) Page 28 Table 4.1 Results of DSC analysis of mm cast rods of binary alloys in the Cu8Zr3-Cu10Zr7 eutectic system. The liquidus temperature Tl was obtained from Zr-Cu phase diagram [Ref. 89]. Page 51 Table 4.2 Summary of results of morphology observations, DSC and DTA analysis of mm cast rods of typical Zr-CuAl alloys in the τ3-τ5-ZrCu eutectic system. Page 69 Table 4.3 Summary of results of morphology observations, DSC and DTA analysis of mm cast rods of typical Zr-CuAl alloys in the τ5-ZrCu-Cu10Zr7 eutectic system. Page 75 Table 4.4 Summary of results of morphology observations, DSC and DTA analysis of mm cast rods of typical Zr-CuAl alloys in the τ3-Zr2Cu-ZrCu eutectic system. Page 82 ix (d) τ3-Zr2Cu-ZrCu system Similarly, by implementing the microstructure-based strategy as stated in the previous two sections and summarized in Figure 5.4.8, the optimum glass forming region, comprising of Zr54Cu38Al8 (alloy 12), Zr55Cu37Al8 (alloy 75) and Zr56Cu36Al8 (alloy 14), in the τ3-Zr2Cu-ZrCu eutectic system was pinpointed. However, according to our results, in the region connecting the optimum glass formers and Zr2Cu (alloys 17 and 20 in Figure 5.4.8), the mm composite (Zr2Cu distributed in glass matrix) was not obtained as in the center part of mm cast rods of alloys 17 and 20. Instead, a fully crystalline region existed, which mainly consisting of Zr2Cu primary phase. This inconsistency with Figure 5.4.4 may have resulted from the sharp drop of the Tg value in this region. According to Ma,13,98-100 the higher the Tg value compared with that of Te (eutectic temperature), the higher the competing ability of glass formation over eutectic coupled growth. Thus, a small fluctuation of Tg value should be the requirement for the optimum glass-forming zone/composition to be enclosed by the compositions that have the ability to form similar-sized glass matrix composites. As shown in Table 4.4 on page 90, the drop of the Tg value from alloy 75 (688K) to alloy 17 (671K) and alloy 20 (659K) is 17 K and 29 K, which are much shaper compared with the drop of the Tg value from alloy 75 (688K) to alloy 71 (684K) and alloy 28 (677K). This sharp decrease of Tg value in the region connecting alloys 14, 75, 12 and Zr2Cu may greatly deteriorate the competing ability of the glass formation over the ternary eutectic coupled growth making alloys 17 and 20 unable to form mm composite (Zr2Cu + glass matrix). However, for mm cast rods of alloys 17 and 20, although mm (Zr2Cu + glass) composite has not been found under our experimental condition, 137 (c) τ3 (b) Intensity (d) Alloy 10 (a) ŒŒ T τ5 τ3 V (Zr51Cu28Al21) 0.5 mm Œτ3 30 alloy75 TZrCu alloy28 VZr Cu alloy20 T V V 40 50 2θ60 (e) Alloy 72 alloy10 VV V 70 80 A+τ 10 72 mm Fully G 14 75 12 0.5 mm 17 20 71 28 A+ZrCu ZrCu Zr2Cu Cu10Zr (f) Alloy 75 (g) Alloy 17 (i) Alloy 71 0.5 mm 0.5 mm Figure 5.4.8: Morphological change of mm cast rods in (h) Alloy 20 (j) Alloy 28 the τ3-Zr2Cu-ZrCu system: (a) The optimum glass forming region is at the junction where the two composite (primary phase τ3, ZrCu in glass matrix) zones meet. (b) The 0.5 mm 0.5 mm XRD patterns of alloys 10, 75, 28 and 20, (c) The morphology of τ3 in glass matrix under high magnification. (d) to (j) A quarter of the cross section of alloys 10, 72, 75, 17, 20, 71 and 28. 0.5 mm 138 the primary phase in the eutectic matrix is Zr2Cu. This can still give us enough of a hint that the change of the primary phase in glass/eutectic matrix from τ3 (alloy 72) to ZrCu (alloy 71), then to Zr2Cu (alloy 17) should encompass the optimum glass formers in the τ3-Zr2Cu-ZrCu eutectic system. 5.4.3 Other considerations (a) Composite formation Our microstructure-based strategy to pinpoint the optimum glass former also shows the compositional region where the glass matrix composite can be obtained. Here the glass matrix composite is defined as an ingot with its primary phase in an amorphous matrix with the most important feature being that there is still amorphous phase at the central part of the ingot. The morphology of the primary phases can be varied and their distribution can be uniform (e.g. Figure 4.3.5) or non-uniform (e.g. Figure 4.3.13). Furthermore, GFA of these glass matrix composites can be very poor, i.e. the critical size for full glass formation is very small. This understanding will aid to locate the alloys with the in situ formed crystalline phase in amorphous matrix, which have been reported to improve the mechanical properties.13,111-113 On the other hand, our microstructure-based strategy to pinpoint the optimum glass former shows that the appearance of crystalline peaks in the XRD pattern should not be regarded as a sign for poor GFA for a given system. It is essential to reveal if the ingot has a composite-like structure, as defined above, through the metallographic inspection of the ingot. Such a composite microstructure actually is an indication that a 139 fully amorphous alloy is nearby. More specifically, controlling the alloy composition towards the direction where the amount of the crystalline phase is diminishing is the correct approach, rather than reducing the ingot size to find the full glass formation in the composite forming alloys, which may have a quite poor GFA for full glass formation. (b) Strong dependency of GFA on alloy composition in ternary alloy systems The fact that there is a at% interval between locating the optimum glass former in ZrCu-Al alloys indicates the same strong GFA dependency on the composition in ternary alloy systems as discovered in binary Cu8Zr3-Cu10Zr7 eutectic system. For the ternary τ3τ5-ZrCu eutectic system, only alloy 67 (Zr48Cu45Al7) can form mm fully glass cast rod; a deviation of only at% will cause the appearing of crystalline phase in mm cast rods (τ3 phase in alloy 64, ZrCu phase in alloys 56 and 45). For the ternary τ5-ZrCu-Cu10Zr7 eutectic system, only alloy 47 (Zr45Cu49Al6) can form mm fully glass cast rod; deviation of only at% will cause the appearance of crystalline phase in mm cast rods (τ5 phase in alloy 49, ZrCu phase in alloy 66 and Cu10Zr7 phase in alloy 59). Greer’s confusion theory for glass formation62 has been widely accepted, leading to the common belief that multi-component alloys are generally preferred in discovering large sized amorphous ingots. Our results here indicate that there is a need to fine tune the composition to achieve optimum glass forming alloys, even at at% interval, because of the strong GFA dependency on the composition; otherwise, the optimum glass forming alloys can be missed, not only in binary alloys as stated in section 5.2.5, but also in multicomponent alloys. For example, as shown in Figure 5.4.5, our optimum glass forming alloy Zr48Cu45Al7 of mm fully glass ingot in the τ3-τ5-ZrCu system is only at% of Zr 140 away from previously reported alloy Zr47Cu46Al7 with significantly lower GFA of mm fully glass rod.38 Similarly, our optimum glass former in the τ5-ZrCu-Cu10Zr7 system. Zr45Cu49Al6 of mm fully glass rod is also at% of Al away from previously reported alloy Zr45Cu50Al5 forming only mm fully glass rod.84 In addition, a new optimum glass forming region (Zr54Cu38Al8, Zr55Cu37Al8 and Zr56Cu36Al8, mm BMGs in the τ3-Zr2CuZrCu system) nearby is also discovered. In all these cases, carefully monitoring the microstructural changes in the cast rods as function of alloy content with at% interval leads us to the optimum glass forming alloys, better than reported before. Although this requirement of scanning the alloys with at% interval in multi-component alloy system may lead to an astronomical number of alloys that need to be studied, our strategy here points out that as long as there is awareness that each of optimum glass former is associated with one eutectic (sometimes a metastable or a pseudo one) and the right way to approach it, i.e. monitoring the microstructure evolution, the task becomes much simpler, at least much more straightforward with some degree of certainty. 141 Chapter Conclusions 1. Based on the principle of the competition of the formation/growth of glass and crystalline phases, metallographic strategies to pinpoint the optimum glass former within binary and ternary eutectic alloy systems have been established. 2. Through implementation of our metallographic strategy, the optimum glass former in the Cu8Zr3-Cu10Zr7 eutectic system, Zr35.5Cu64.5, has been pinpointed. This alloy can form bulk metallic glass with mm in diameter and has broken the empirical condition previously believed necessary for BMG formation, i.e. a multi-component recipe with at least three components. Any alloy in the Cu8Zr3Cu10Zr7 eutectic system deviating from Zr35.5Cu64.5 even by 0.5 at% failed to form mm BMG. On each side of Zr35.5Cu64.5, a composition zone forming mm BMG composites (Cu8Zr3 + glass or Cu10Zr7 + glass) has been found, in which the volume percentage of the crystalline phase decreased when the composition was nearer to Zr35.5Cu64.5. 3. By implementing our metallographic strategy, we have pinpointed three optimum glass forming regions, in three adjacent Zr2Cu-τ3-ZrCu, τ3-τ5-ZrCu and τ5-ZrCuCu10Zr7 eutectics in the ternary Zr-Cu-Al alloy system. Any alloy deviating from these compositions by even at% was found to have a significantly lower GFA. 142 The optimum glass forming alloys were surrounded by the alloys forming crystalline plus amorphous composite with similar critical size. 4. In both the binary and ternary eutectic systems we studied, the composite defined as primary phase in amorphous matrix can be obtained in the alloys close to the optimum glass former, but lying in the region between the optimum glass former and the corresponding primary crystalline phase. The distribution of the primary phase was found to be either uniform or non-uniform. This understanding will aid to locate the alloys with the in situ formed crystalline phase in amorphous matrix. 5. Our present results indicate that there is a strong dependency of GFA on composition in both binary and ternary alloy systems. This strong dependency can not be accounted for by the commonly used parameters, at least not in our present study. Although the requirement of changing the alloy content with 0.5 at% interval in binary alloy systems and at% interval in ternary alloy systems leads to a large number of alloys that need to be studied, our finding points out that as long as we are aware that each of optimum glass former is associated with one eutectic, the task becomes much simpler. 6. The present study shows that neither of the GFA scaling parameters, Trg and ∆Tx values, can represent the relative GFA of our studied alloys. 143 Future Work (a) Study of the mechanical properties of the bulk metallic glasses and the bulk metallic glass matrix composites obtained in this work A major drawback of bulk metallic glasses for engineering applications is the low ductility under tensile or compressive loading at ambient temperature. To counter this, the introduction of a crystalline phase into the glass matrix has been utilized to improve the ductility of bulk metallic glasses. However, although prior works have demonstrated the benefit of the crystalline reinforcement in bulk metallic glasses, there has yet to be a systematic study of the role of the crystalline reinforcement volume fraction on various properties. The bulk metallic glass matrix composites obtained in this work with different volume fraction of crystalline phase offers ample room for the systematic study of the volume-fraction effects on the mechanical properties of bulk metallic glass matrix composites. (b) Application of the strategy established in this work to other binary eutectic systems It should be promising to obtain more binary bulk metallic glasses if our metallographic strategy for pinpointing the optimum glass former is implemented to other 144 binary eutectic alloy systems. Moreover, those systems having been scrutinized before should also be included, because the strong dependence of GFA on the composition observed in this work implies that many good BMG formers may have escaped detection. With the formation of these binary bulk metallic glasses, the atomic-level short-range structures, thermodynamic modeling, and computer simulations would become readily tractable for the BMG family. This is because of the avoidance of the difficulties encountered for the BMGs so far due to the complex nature of the multi-component interactions involved. (c) Study of the glass forming ability of Zr based quaternary alloys The ternary Zr based optimum glass formers pinpointed in this work form the real starting point for further improvement of GFA of quaternary Zr based alloys. 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Composition Zr Cu Al 62 56 52 36 42 46 2 48 46 44 42 50 52 54 56 2 2 62 60 58 54 52 34 36 38 42 44 4 4 50 49 47 46 44 42 50 49 47 46 45 44 43 46 47 49 50 52 54 45 46 48 49 50 51 52 4 4 4 5 5 5 60 58 56 54 52 34 36 38 40 42 6 6 50 49 48 47 44 45 46 47 6 6 Tm (K) Tl (K) One melting peak (Yes or No) 1124 1124 1122 1139 1141 1140 1139 1122 1123 1124 1122 1124 1127 1126 1140 1139 1141 1141 1123 1126 1138 1140 1140 1141 1140 1122 1124 1121 1122 1123 1124 1126 1125 1139 1280 1250 1222 1230 1202 1189 1194 1264 1256 1248 1218 1219 1207 1208 1202 1200 1190 1193 1194 1195 1195 1191 1185 1189 1191 1252 1245 1227 1208 1209 1191 1187 1192 1189 No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No 150 Composition Zr Cu Al 46 45 44 43 48 49 50 51 6 6 54 52 39 41 7 50 49 48 47 46 45 44 43 43 44 45 46 47 48 49 50 7 7 7 7 58 56 55 54 52 34 36 37 38 40 8 8 50 49 48 47 45 44 43 56 54 52 50 48 46 44 42 42 43 44 45 47 48 49 34 36 38 40 42 44 46 48 8 8 8 10 10 10 10 10 10 10 10 54 52 34 36 12 12 50 48 46 38 40 42 12 12 12 54 32 14 50 48 36 38 14 14 Tm (K) Tl (K) One melting peak 1139 1140 1140 1140 1122 1123 1122 1126 1125 1130 1140 1142 1141 1142 1122 1121 1121 1122 1123 1124 1125 1125 1125 1139 1139 1140 1121 1123 1121 1124 1126 1125 1142 1140 1122 1121 1122 1125 1124 1122 1121 1125 1186 1178 1183 1187 1199 1192 1181 1184 1186 1187 1187 1188 1204 1212 1231 1212 1208 1190 1180 1179 1177 1197 1218 1195 1212 1219 1194 1176 1163 1176 1206 1223 1252 1260 1188 1182 1170 1258 1267 1198 1188 1159 No Yes Yes No No No No No No No No No No No No No No No No No No No No No No No No Yes Yes No No No No No No No No No No No No Yes 151 Composition Zr Cu Al 46 40 14 52 32 16 50 48 46 50 46 44 46 34 36 38 32 36 38 34 16 16 16 18 18 18 20 Tm (K) Tl (K) One melting peak 1125 1123 1123 1123 1125 1123 1124 1124 1125 1272 1208 1209 1192 1172 1227 1195 1270 1220 No No No No No No No No No 152 [...]... points found at Zr5 2Cu3 8Al1 0 (alloy 6), Zr4 8Cu3 8Al1 4 (alloy 3) and Zr4 5Cu4 9Al6 (alloy 47) respectively Page 46 Figure 4.2.2 DTA melting curves of Zr4 8Cu3 8Al1 4 (alloy 3) and its three surrounding alloys, Zr4 6Cu3 8Al1 6, Zr5 0Cu3 6Al1 4 and Zr4 8Cu4 0Al1 2 Page 47 Figure 4.2.3 DTA melting curves of alloy 47 (Zr4 5Cu4 9Al6 ), and its three surrounding alloys, Zr4 5Cu4 7Al8 , Zr4 7Cu4 9Al4 and Zr4 3Cu5 1Al6 Page 48 Figure... the τ3 (Zr5 1Cu2 8Al2 1)-τ5 (Zr3 8Cu3 6Al2 6)-ZrCu, τ5-ZrCu -Cu1 0Zr7 and τ 3Zr2 Cu- ZrCu systems The last one, from Section 4.3 to Section 4.5, shows the GFA change of the studied Zr- Cu- Al alloys in the τ3 (Zr5 1Cu2 8Al2 1)-τ5 (Zr3 8Cu3 6Al2 6)-ZrCu, τ5ZrCu -Cu1 0Zr7 and τ3 -Zr2 Cu- ZrCu ternary eutectic systems The reason to focus on ternary systems is mainly that ternary system is the simplest multi-component system and the... Figure 4.3.7 DSC curves of 5 mm cast rods of alloy 8 (Zr5 0Cu3 4Al1 6), alloy 2 (Zr5 0Cu3 6Al1 4), alloy 1 (Zr5 0Cu3 8Al1 2), alloy 7 (Zr5 0Cu4 0Al1 0) and alloy 55 (Zr5 0Cu4 3Al7 ) Page 56 Figure 4.3.8 XRD patterns of 5 mm cast rods of alloy 11 (Zr4 6Cu4 2Al1 2), alloy 39 (Zr4 6Cu4 4Al1 0) and alloy 40 (Zr4 7Cu4 5Al8 ) showing the decrease of the intensity of crystalline diffraction peaks from alloy 11 to alloy 40 Page 57... (Zr5 0Cu3 6Al1 4), alloy 1 (Zr5 0Cu3 8Al1 2), alloy 7 (Zr5 0Cu4 0Al1 0) and alloy 55 (Zr5 0Cu4 3Al7 ) showing the decrease of the intensity of crystalline diffraction peaks from alloy 8 to alloy 55 Page 51 Figure 4.3.4 Optical photos of about a quarter part of the transversal cross section of 5 mm cast rods of alloy 8 (Zr5 0Cu3 4Al1 6), alloy 2 (Zr5 0Cu3 6Al1 4), alloy 1 (Zr5 0Cu3 8Al1 2), alloy 7 (Zr5 0Cu4 0Al1 0) and alloy... (a) alloy 64 (Zr4 9Cu4 4Al7 ), (b) alloy 67 (Zr4 8Cu4 5Al7 ), (c) alloy 56 (Zr4 9Cu4 5Al6 ) and (d) alloy 45 (Zr4 8Cu4 6Al6 ) under high magnification Page 65 Figure 4.3.19 DSC curves of 5 mm cast rods of alloys 64 (Zr4 9Cu4 4Al7 ), 67 (Zr4 8Cu4 5Al7 ), 56 (Zr4 9Cu4 5Al6 ) and 45 (Zr4 8Cu4 6Al6 ), exhibiting a strong crystallization event Page 65 Figure 4.3.20 Trend in GFA change of alloys in the τ3-τ5-ZrCu eutectic system and. .. (Zr5 4Cu3 8Al8 ), (b) alloy 75 (Zr5 5Cu3 7Al8 ) and (c) alloy 14 (Zr5 6Cu3 6Al8 ) at high magnification Page 86 Figure 4.5.5 DSC curves of 5 mm cast rods of alloys 12 (Zr5 4Cu3 8Al8 ), 75 (Zr5 5Cu3 7Al8 ) and 14 (Zr5 6Cu3 6Al8 ), exhibiting a strong crystallization event Page 86 Figure 4.5.6 XRD patterns of 5 mm cast rods of alloys 10 (Zr5 4Cu3 4Al1 2) and 72 (Zr5 4Cu3 6Al1 0), showing the decrease of the intensity of crystalline... mm cast rods of (a) alloy 57 (Zr4 9Cu4 6Al5 ) and (b) alloy 62 (Zr4 9Cu4 7Al4 ) at high magnification Page 62 Figure 4.3.15 DSC curves of 5 mm cast rods of alloy 57 (Zr4 9Cu4 6Al5 ) and alloy 62 (Zr4 9Cu4 7Al4 ) Page 63 Figure 4.3.16 XRD patterns of 5 mm cast rods of alloys 64 (Zr4 9Cu4 4Al7 ), 67 (Zr4 8Cu4 5Al7 ), 56 (Zr4 9Cu4 5Al6 ) and 45 (Zr4 8Cu4 6Al6 ), showing a typical broad hump without any visible crystalline diffraction... (Zr4 6Cu4 2Al1 2), and the composite region (τ5 distributed in amorphous matrix) in the central part of 5 mm cast rods of (b) alloy 39 (Zr4 6Cu4 4Al1 0), (c) alloy 40 (Zr4 7Cu4 5Al8 ) Page 60 Figure 4.3.11 DSC curves of 5 mm cast rods of alloy 11 (Zr4 6Cu4 2Al1 2), alloy 39 (Zr4 6Cu4 4Al1 0) and alloy 40 (Zr4 7Cu4 5Al8 ) Page 60 Figure 4.3.12 XRD patterns of 5 mm cast rods of alloy 57 (Zr4 9Cu4 6Al5 ) and alloy 62 (Zr4 9Cu4 7Al4 )... showing the 2 mm fully glass forming zone and 2 mm glass matrix composite forming zones (glass + Cu 8Zr3 , glass + Cu1 0Zr7 ) in the Cu 8Zr3 -Cu1 0Zr7 eutectic system (A: Amorphous) Page 112 Figure 5.3.1 Tg and Tl isotherms of the τ3 -Zr2 Cu- ZrCu, τ3-τ5-ZrCu and τ5-ZrCu -Cu1 0Zr7 eutectic systems Page 115 Figure 5.3.2 Tx and Tl isotherms of the τ3 -Zr2 Cu- ZrCu, τ3-τ5-ZrCu and τ5-ZrCu -Cu1 0Zr7 eutectic systems Page... central part of 5 mm cast rods of alloy 43 (Zr4 5Cu4 7Al8 ) and (b) alloy 49 (Zr4 5Cu4 8Al7 ) at high magnification Page 77 Figure 4.4.7 DSC curves of 5 mm cast rods of alloys 43 (Zr4 5Cu4 7Al8 ) and 49 (Zr4 5Cu4 8Al7 ) Page 77 Figure 4.4.8 XRD patterns of 5 mm cast rods of alloys 65 (Zr4 7Cu4 9Al4 ) and 66 (Zr4 6Cu4 9Al5 ) Page 78 xvi Figure 4.4.9 Optical photos of about a quarter part of the transversal cross section of . patterns of 5 mm cast rods of alloys 65 (Zr 47 Cu 49 Al 4 ) and 66 (Zr 46 Cu 49 Al 5 ). Figure 4.4.8 Page 78 DSC curves of 5 mm cast rods of alloys 43 (Zr 45 Cu 47 Al 8 ) and 49 (Zr 45 Cu 48 Al 7 ) melting curves of alloy 6 (Zr 52 Cu 38 Al 10 ), and its three surrounding alloys, Zr 50 Cu 40 Al 10 , Zr 52 Cu 36 Al 12 and Zr 54 Cu 38 Al 8 . Figure 4.2.4 Page 48 DTA melting curves of alloy. 47 (Zr 45 Cu 49 Al 6 ), and its three surrounding alloys, Zr 45 Cu 47 Al 8 , Zr 47 Cu 49 Al 4 and Zr 43 Cu 51 Al 6 . Figure 4.2.3 Page 48 DTA melting curves of Zr 48 Cu 38 Al 14 (alloy