초록 ▼

1. 전이원소계열 하이엔트로피 합금을 개발하여 국제 하이엔트로피 합금 방사선 조사 저항성 이슈대응 follow-up 연구.
2. 기존의 원자력 소재가 적용 불가능한 가혹한 환경에서의 미래형 원자로 소재로 방사선 손상에 대해 자가치유 효과를 갖는 고온 안정성 refractory 하이엔트로피 합금을 개발함.
3. 중성자회절단면적, 혼합엔탈피, BCC 상 형성을 기준으로 Al, Ti, V, Zr, Nb, Mo을 선택하여 4단계, 60여종의 합금개발을 통해 조성 최적화.
4. 개발된 6성분계 하이엔트로피 합금은 우수한 상온

1. 전이원소계열 하이엔트로피 합금을 개발하여 국제 하이엔트로피 합금 방사선 조사 저항성 이슈대응 follow-up 연구.
2. 기존의 원자력 소재가 적용 불가능한 가혹한 환경에서의 미래형 원자로 소재로 방사선 손상에 대해 자가치유 효과를 갖는 고온 안정성 refractory 하이엔트로피 합금을 개발함.
3. 중성자회절단면적, 혼합엔탈피, BCC 상 형성을 기준으로 Al, Ti, V, Zr, Nb, Mo을 선택하여 4단계, 60여종의 합금개발을 통해 조성 최적화.
4. 개발된 6성분계 하이엔트로피 합금은 우수한 상온/고온 기계적 특성을 보임.
5. Refractory 하이엔트로피 합금의 원자가전자농도가 연성의 핵심 요소임을 발견하고, 원자가 전자농도와 고용강화효과를 고려하여 연성, 강도를 동시에 최적화 합금설계법을 제시.
6. 추후 고온 기계적 특성 및 내산화성을 획기적으로 향상시키기 위한 합금 개발 방향으로 ODS 합금화, 초합금화 및 Silicide 부동태 피막 형성 연구를 제안함.
(출처:요약서 3p)

Abstract ▼

Ⅰ. Introduction
- In this study, self-healing high entropy alloys against radiation damage was developed as a new breakthrough nuclear material. Research includes (1) survey of technological status in international and domestic fields of relevance, (2) development of transition metal elements bas

Ⅰ. Introduction
- In this study, self-healing high entropy alloys against radiation damage was developed as a new breakthrough nuclear material. Research includes (1) survey of technological status in international and domestic fields of relevance, (2) development of transition metal elements based high entropy alloys for following-up global trend of research on irradiation resistance of high entropy alloys, (3) development of refractory metal elements based high entropy alloys for generation 4 nuclear reactor, (4) evaluation of developed high entropy alloys for nuclear reactor and suggestion for further development.
- In generation 4 nuclear reactors which have been the subject of active research due to high efficiency and safty, the materials face extreme environment with high temperature ( 400~1000℃ ) and high irradiation dose ( 40~200dpa ). The condition is consistently becoming severe to get higher efficiency, and it is difficult for existing nuclear materials such as F/M steel, Ni-based superalloy, Zr alloy, V alloy, etc, to withstand the hard condition. Thus development of new alloys which is tolerant to such conditions is important.
- Breaking the traditional alloy design trend, novel high-entropy alloys which have multi-major components with similar atomic ratio have precise properties including high strength, toughness in wide temperature range. Furthermore, it has been simulated that high entropy alloy has self healing effects of radiation damages. Therefore, high entropy alloys are getting more attention as a new candidate material for next generation nuclear reactors.
- However, irradiation resistance of high entropy alloys has been usually investigated in transition metal based high entropy alloy systems, which are difficult to be used as nuclear materials. Therefore, it is crucial to develop new high entropy alloys with refractory elements, which have high melting points with high thermal stability leading to superior high temperature mechanical properties.

Ⅱ. Contents
Past studies and projects on high entropy alloys are centered around simple alloy design by changing compositions and mechanical tests to appeal the superiority of developed alloys. Since 2012, more complicated researches, such as fundamental aspects, composite structure, application, have been performed in transition metal elements based high entropy alloys. On the other hand, since first reported at 2011, researches on refractory high entropy alloys have been about simple fabrication and mechanical tests. Nowadays, in our point of view, the amount of results are enough to be collected to find the fundamental and interesting trends of refractory high entropy alloys. Although most researches about irradiation resistance of high entropy alloys are for fcc alloys with transition metal elements, the real application of high entropy alloys would be realized with refractory metal elements based high entropy alloys. Thus, we divided our research contents into three scheme. First, we discussed the self healing behavior of high entropy alloys in extreme environment by high pressure torsion, which sometimes be used as semi-irradiation test. Second, we developed fcc high entropy alloy series with transition metal elements to follow up the newest discussion. Third, we developed bcc high entropy alloy series with refractory metal elements to apply / find the applicability for nuclear materials. The summarized results are discussed in the following section.

○ High entropy alloys showed lower defect concentration after high pressure torsion. For the phase stability of high entropy alloy, high temperature phase was stabilized after high pressure torsion. Both phenomena could be explained by sluggish diffusion aspect, which is consistent to the atomic level stress concept suggested as the origin of self healing behavior of high entropy alloy.
○ New transition metal based high entropy alloy with twin induced plasticity without losing strength was developed by considering solid solution hardening and stacking fault energy.
○ New refractory high entropy alloys were developed by considering neutron absorption area, formation enthalpy and tendency to form bcc crystal structure.
○ The refractory high entropy alloy showed both of good ductility and high strength in the composition range of Al-5at%, 10at%○ The alloy would be further developed with combing the concepts of oxide dispersion strengthened, superalloy, and silicide.

Ⅲ. Expected
As a frontier of materials research, the field of high-entropy alloys is in the beginning stage. The development of self-healing high entropy alloy with high radiation damage resistance and thermal stability may provide reliability and predictability as new nuclear materials. Indeed, our research results show that the application of these paradigm-shifting materials can be greatly extended by utilizing the self-healing behavior of high entropy alloys. This would in turn permit a more widespread and cost-effective application in various industries with extreme conditions such as space industry and nuclear industry. Utilization of high entropy alloy in structural metallic alloys may present a new breakthrough application of metallic materials in the near future.
(출처:SUMMARY 8~10p)

목차 Contents

• 표지 ... 1
• 제출문 ... 2
• 보고서 요약서 ... 3
• 요약문 ... 4
• Summary ... 8
• CONTENTS ... 11
• 목차 ... 12
• 제1장 연구개발과제의 개요 ... 13
• 1절 연구개발의 목적 ... 13
• 2절 연구개발의 필요성 및 범위 ... 13
• 제2장 국내외 기술개발 현황 ... 18
• 1절 국내외 관련분야에 대한 기술개발현황 ... 18
• 2절 현재 연구결과가 국내외 기술개발현황에서 차지하는 위치 ... 19
• 제3장 연구개발수행 내용 및 결과 ... 21
• 1절 하이엔트로피 합금에 관한 배경 이론 및 자료 정리 ... 21
• 2절 하이엔트로피 합금의 방사선 조사 특성 모사실험 ... 29
• 3절 전이원소계 FCC 하이엔트로피 합금 개발 ... 45
• 4절 내화금속계 BCC 하이엔트로피 합금 개발 ... 73
• 5절 비정질 합금의 이온빔 조사 실험 ... 104
• 6절 고온 극한환경용 원자력 신소재로 응용을 위한 개발 합금의 종합평가 ... 108
• 7절 원자로 응용을 위한 추가 요소 예비 연구 ... 110
• 제4장 목표달성도 및 관련분야에의 기여도 ... 116
• 1절 목표달성도 ... 116
• 2절 관련분야에의 기여도 ... 120
• 제5장 연구개발결과의 활용계획 ... 121
• 제6장 연구개발과정에서 수집한 해외과학기술정보 ... 122
• 제7장 연구장비의 구축 및 활용 결과 ... 125
• 제8장 참고문헌 ... 126
• 끝페이지 ... 129