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yjsweetsmile铁虫 (正式写手)
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[求助]
求摘要：国家自然科学基金50625103
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bird168
铁杆木虫 (著名写手)
- 基金HEPI: 5
- 应助: 12 (小学生)
- 贵宾: 0.01
- 金币: 9857.2
- 散金: 110
- 红花: 10
- 帖子: 2208
- 在线: 961.5小时
- 虫号: 636208
- 注册: 2008-10-25
- 性别: GG
- 专业: 凝聚态物性 II ：电子结构
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wg423(悬赏金币+20, 基金HEPI+1): 协助结贴，谢谢应助 2013-03-31 20:29:21
wg423(悬赏金币+20, 基金HEPI+1): 协助结贴，谢谢应助 2013-03-31 20:29:21
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中文摘要： 1) 选取并设计了典型的FCC金属或合金，如Al、Ag、Au、Cu、Ni、Cu-Al、Cu-Zn合金等单晶体，从元素类型和晶体取向两方面揭示了FCC金属循环形变行为与微观位错组态之间的关系，提出了FCC金属疲劳微观缺陷演化的一般规律。 2) 研究了具有不同晶体取向的平行、垂直和倾斜晶界铜双晶体的循环应力 - 应变响应、位错组态、驻留滑移带与晶界、孪晶界的交互作用、沿晶和穿晶疲劳开裂机理。 3) 证实了统一拉伸断裂准则的有效性，提出临界解理强度σ0和剪切强度τ0为同种材料中两个独立的本征强度，提出了剪切-解理因子是控制材料强度、塑性和断裂方式的重要参数。 4) 提出非晶合金塑性临界剪切台阶的概念，设计了100纳米尺寸非晶样品的原位拉伸实验，观察到非晶合金的拉伸塑性、稳定剪切与颈缩现象。 5) 研究了不同FCC金属与合金的孪生与滑移的竞争关系，揭示了金属层错能、晶粒尺寸和晶体取向对FCC金属形变孪生的影响。 6) 通过设计铜铝与铜锌合金的层错能，发现经过ECAP及HPT挤压后强度和均匀延伸率随合金增加而同步增加，并且也能提高其疲劳强度。 中文主题词： 疲劳；断裂；强度；塑性 英文摘要: The fatigue damage mechanisms and dislocation evolution of dislocations in various fcc metals (Al, Cu, Ag, Au, Ni, Cu-Al and Cu-Zn) were investugated. The general rule of dislocation evoluation was proposed based on the results above. The cyclic deformation behaviors of copper bicrystals with parallel, perpendicuar and inclined GBs were investigated, including cyclic stress-strain response, dislocations and interactions of PSB with GBs and TBs to reveal the fatigue cracking mechanisms. The unified tensile fracture criterion was confirmed and the two intrinsic strengths were proposed to control the materials of materials. The concept of the critical shear step in metallic glass was proposed and tensile plasticity of nano-pillar metallic glass as well stable shearing and necking was observed by in-situ tension test. The compition between slipping and twinning in fcc metals were investigated and the efects of stacking fault energy, grain size and orientation were proposed to affect the twnning mechanism in materials with different grain size. The strength and elongation of Cu-Al and Cu-Zn alloys were investigated agter ECAp and HPT processing. It is found that both the strength and elongation of the Cu-Al and Cu-Zn alloys increase with increasing alloying elements. Furthermore, the fatigue strength also increases with adding more alloy elements. 英文主题词： Fatigue; Fracture; Strength, Plast |
2楼2013-02-22 20:58:00
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