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首页> 外文OA文献 >Microstructure, Thermal Stability and Consolidation of Nanostructured and Ultrafine Structured Cu based Metal Matrix Composite and Alloy Powders Produced by High Energy Mechanical Milling
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Microstructure, Thermal Stability and Consolidation of Nanostructured and Ultrafine Structured Cu based Metal Matrix Composite and Alloy Powders Produced by High Energy Mechanical Milling

机译：高能机械研磨制备的纳米结构和超细结构的铜基金属基复合材料和合金粉末的微观结构，热稳定性和固结

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摘要

Ultrafine grained and/or nanostructured Cu and Cu-(2.5-10)vol.%Al2O3 composite balls/granules/powder particles were produced using two high energy mechanical milling (HEMM) routes respectively. The microstructural evolution of the as-milled Cu and Cu-Al2O3 composite balls/granules/powder particles produced using Route 1 (12hours) and Route 2 (Route 1 + 12 hours milling under another condition) of milling was studied using scanning electron microscopy (SEM), transmission electron microcopy (TEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray (EDX) mapping. The study confirmed that HEMM can be effectively used to disperse (2.5-10)vol.%Al2O3 nanoparticles into a ultrafine grained or nanocrystalline Cu matrix after both routes of milling.The as-milled Cu and Cu-Al2O3 composite balls/granules/powder particles were heat treated at 150, 300, 400 and 500 C for 1 hour, respectively, to determine the thermal stability of the microstructure and corresponding microhardness change as a function of annealing temperature. It was found that for Cu and Cu-2.5vol.%Al2O3 composites after heat treatment at 150 C, the Cu grain sizes decreased due to recrystallisation, and increasing the annealing temperature to 300 C causes slight coarsening of the Cu grains. Further increasing the annealing temperature to 500 C caused significant coarsening of the Cu grains and the Al2O3 nanoparticles. With increasing the volume fraction of Al2O3 nanoparticles, (i) the thermal stability of the Cu-Al2O3 composite increases, (ii) the microstructure of the Cu matrix became finer, and (iii) the coarsening of Cu grains in the composite powder particles after annealing at 500 C become less severe.The average microhardness of the Cu-Al2O3 composites decreased after annealing at 150 C due to decrease of dislocation density, then remained almost unchanged with increasing the annealing temperatures to 300 C and 400 C. Further increasing the annealing temperature to 500 C caused significant decrease in average microhardness due to reduction in dislocation density and grain coarsening, suggesting that Cu-Al2O3 composites are thermally stable at temperatures up to 400 C.Pure copper powder and Cu-Al2O3 composite powders produced using Route 2 were compacted by hot pressing at 350 C followed powder compact forging. Increasing the volume fraction of Al2O3, the average microhardness increased for the forged Cu-Al2O3 composites. A decrease in tensile fracture strength was examined for the Cu-Al2O3 composites with the increase of the volume fraction of Al2O3 as 2.5% to 10%.Nanostructured Cu-(1-4)at.%Pb alloy powder particles were produced using Route 1 of high energy mechanical milling. The microstructural evolution and thermal stability of microstructure of powder particles as a function of annealing temperature were examined. It was found that heat treatment at 150 C caused slight coarsening of the Cu grains, and increasing the annealing temperatures to 300 and 500 C caused significant coarsening of the Cu grains. The average microhardness of the Cu-Pb alloy powder particles decreased after annealing at 150 C due to decrease of dislocation density, and then remained almost unchanged with increasing the annealing temperature to 300 C. Further increasing the annealing temperatures to 400 C and 500 C caused significant decrease in average microhardness due to reduction in dislocation density and grain coarsening, suggesting that Cu-Pb alloy powders are thermally stable at temperatures up to 300 C.
机译：分别使用两种高能机械研磨（HEMM）路线生产了超细晶粒和/或纳米结构的Cu和Cu-（2.5-10）％（体积）Al2O3复合球/颗粒/粉末颗粒。使用扫描电子显微镜研究了使用铣削路线1（12小时）和路线2（在另一种条件下路线1 + 12小时铣削）生产的已研磨的Cu和Cu-Al2O3复合球/颗粒/粉末颗粒的显微组织演变（使用扫描电子显微镜（ SEM），透射电子显微镜（TEM），扫描透射电子显微镜（STEM）和能量色散X射线（EDX）映射。研究证实，HEMM可以有效地将（2.5-10）vol。％的Al2O3纳米颗粒分散到超细晶粒或纳米晶态的Cu基体中，经过两种铣削路径后均可研磨.Cu和Cu-Al2O3复合球/颗粒/粉末分别在150、300、400和500℃下热处理1小时，以确定组织的热稳定性以及相应的显微硬度随退火温度的变化。发现对于在150℃下热处理的Cu和Cu-2.5vol。％Al 2 O 3复合材料，由于重结晶而使Cu晶粒尺寸减小，并且将退火温度升高至300℃导致Cu晶粒略微粗大化。将退火温度进一步提高到500°C会导致Cu晶粒和Al2O3纳米颗粒的明显粗化。随着Al2O3纳米颗粒体积分数的增加，（i）Cu-Al2O3复合材料的热稳定性增强，（ii）Cu基体的微观结构变得更细，并且（iii）复合粉末中的Cu晶粒粗大化。在500°C下退火变得不那么严重。在150°C退火后，Cu-Al2O3复合材料的平均显微硬度由于位错密度的降低而降低，然后随着退火温度升高至300°C和400°C几乎保持不变。温度升高至500°C会导致位错密度降低和晶粒粗化，从而导致平均显微硬度显着降低，这表明Cu-Al2O3复合材料在最高400°C的温度下具有热稳定性。使用路线2生产的纯铜粉和Cu-Al2O3复合粉通过在350°C的热压进行压实，然后进行粉末压实锻造。增加Al2O3的体积分数，锻造的Cu-Al2O3复合材料的平均显微硬度增加。研究了Cu-Al2O3复合材料拉伸断裂强度的降低，其中Al2O3的体积分数从2.5％增至10％。使用路线1生产了纳米结构的Cu-（1-4）at。％Pb合金粉末颗粒高能机械铣削。研究了粉末颗粒的微观结构演变和热稳定性随退火温度的变化。发现在150℃下的热处理引起Cu晶粒的稍微粗大化，并且将退火温度升高至300℃和500℃导致Cu晶粒的明显粗大化。由于位错密度降低，Cu-Pb合金粉末颗粒的平均显微硬度在150°C退火后降低，然后随着退火温度升高至300 C几乎保持不变。进一步将退火温度升高至400 C和500 C由于位错密度的降低和晶粒的粗化，平均显微硬度显着降低，这表明Cu-Pb合金粉末在高达300 C的温度下具有热稳定性。

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    Mukhtar Aamir;

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  • 年度 2010
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