The effects of annealing on the microstructure and mechanical properties of Al–Zn–Mg–Cu–Si alloys fabricated by high-energy ball milling (HEBM) and spark plasma sintering (SPS) were investigated. The HEBM-free sintered alloy primarily contained Mg2Si, Q-AlCuMgSi, and Si phases. Meanwhile, the HEBM-sintered alloy contains Mg-free Si and θ-Al2Cu phases due to the formation of MgO, which causes Mg depletion in the Al matrix. Annealing without and with HEBM at 500oC causes partial dissolution and coarsening of the Q-AlCuMgSi and Mg2Si phases in the alloy and dissolution of the θ-Al2Cu phase in the alloy, respectively. In both alloys, a thermally stable α-AlFeSi phase was formed after long-term heat treatment. The grain size of the sintered alloys with and without HEBM increased from 0.5 to 1.0 μm and from 2.9 to 6.3 μm, respectively. The hardness of the sintered alloy increases after annealing for 1 h but decreases significantly after 24 h of annealing. Extending the annealing time to 168 h improved the hardness of the alloy without HEBM but had little effect on the alloy with HEBM. The relationship between the microstructural factors and the hardness of the sintered and annealed alloys is discussed.

1. Introduction
2. Experimental
3. Result and Discussion
    3.1 열역학 계산
    3.2 XRD 분석
    3.3 이차상 및 산화물 분석
    3.4 EBSD 활용 결정립 분석
    3.5 기계적 특성
4. Conclusion
Acknowledgement

• 이준호(전북대학교 신소재공학부) | Junho Lee (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea)
• 박성현(전북대학교 신소재공학부) | Seonghyun Park (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea)
• 이상화(전북대학교 신소재공학부) | Sang-Hwa Lee (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea)
• 손승배(전북대학교 신소재공학부, 전북대학교 신소재개발연구센터) | Seung Bae Son (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea , Research Center for Advanced Materials Development, Jeonbuk National University, Jeonju 54896, Republic of Korea)
• 이석재(전북대학교 신소재공학부, 전북대학교 신소재개발연구센터) | Seok-Jae Lee (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea, Research Center for Advanced Materials Development, Jeonbuk National University, Jeonju 54896, Republic of Korea)
• 정재길(전북대학교 신소재공학부, 전북대학교 신소재개발연구센터) | Jae-Gil Jung (Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea, Research Center for Advanced Materials Development, Jeonbuk National University, Jeonju 54896, Republic of Korea) Corresponding author