近幾代超合金之耐溫度已藉由提升晶格係數差異強化γ/γ'介面得以有效提升，此外合金表面也透過選擇性氧化設計得到適當保護。然而，第五代以及第六代超合金中所含的錸及釕等貴重元素限制了其工業應用性。本研究針對傳統第一代超合金利用前所提及之概念提升其晶格係數差異以及選擇性氧化設計以開發新型含矽方向鑄造超合金(KC-5)，期望能提高合金性價比。本論文探討了合金KC-5的抗高溫潛變性質以及氧化表現。相較於CM247LC，KC-5的 γ' 因合金含有較高含量的鈦和鉬而擁有較高的百分比以及方正的形貌。添加鈦、鉬及矽對於合金元素分配係數之影響透過應變時效方法搭配EPMA來解析，並利用高溫XRD分析各合金晶格係數差異之程度。實驗結果顯示合金KC-5展現出較大的晶格係數差異，如此可促成筏排化結構並有效降低潛變應變速率。此外，KC-5經由一小時高溫氧化測試後可觀察到連續的氧化鋁層；但該合金降低了熱處裡窗口以及相穩定性。

Abstract I
Acknowledgements II
List of Figures VII
List of Tables XII
I. Introduction 1
II. Literature Review 4
2.1 Recent development on superalloys 4
2.2 The γ' volume fraction 10
2.3 Lattice misfit between  and  11
2.4 Alloy design tools – JMatPro and Thermocalc 14
2.5 Selective oxidation 17
2.6 Effects of Si addition 19
III. Materials and Methods 21
3.1 Alloy design 21
3.2 Experimental procedure 32
3.3 The design of heat treatment 35
3.4 X-ray diffractometer 37
3.5 Optical metallography (OM) 37
3.6 Scanning electron microscopy (SEM) 37
3.7 Phase stability test 38
3.8 Determine elemental partitioning coefficients 39
3.9 Lattice misfit (unconstrained and constrained values) 41
3.10 Creep test 43
3.11 Oxidation test 43
IV. Results and Discussion 44
4.1 Microstructure evolution 44
4.1.1 As-cast microstructures 44
4.1.2 The thermal properties 53
4.1.3 Microstructures after SHT 57
4.1.4 Double ageings 61
4.1.5 Phase stability 67
4.2 Elemental partitioning and lattice misfit 71
4.2.1 Cellular precipitation of γ' 71
4.2.2 Elemental partitioning coefficients 73
4.2.3 Unconstrained lattice misfit 78
4.2.4 Constrained lattice misfit 81
4.3 Creep behavior 84
4.4 Oxidation behavior 92
Conclusions 96
Future Work 98
References 99

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