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The microstructure and hardness of conventionally solidified Ni-xSi (x = 21.4%, 22%, 24%, 26%) alloys were investigated. The solidification microstructures of different Ni-Si alloys were observed by optical microscope (OM) and scanning electron microscope (SEM) and the phase composition was indentified under the help of energy dispersive X-ray (EDX) analysis. The macro- and micro-hardness of the Ni-Si alloys at room temperature were also examined. The experimental results indicated that both the microstructure and hardness closely depended on the Si content. Due to the vast formation of primary ??-Ni31Si12 phase, the hardness of Ni-26.0%Si alloy was significantly improved compared with that of Ni-21.4%Si eutectic alloy. However, the fracture toughness was greatly weakened simultaneously. The (?? 1-Ni3Si+??-Ni31Si12) lamellar eutectoid structure formed in the primary ??-Ni31Si12 phase exhibited better ductility than single ??-Ni31Si12 phase at the cost of relatively small hardness reduction. 相似文献
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几年来,皖江航运显示出巨大作用。据不完全统计:2005年皖江水系共完成货物运输量5200万吨和8.2亿吨公里,占社会总运量35%。大量的矿建材料、黄砂、石子源源不断地输入上海,有力地支援了浦东建设。进口矿砂大部分都是船运马钢,安庆石化的原油及其制品,也是依靠长江航运进出。安庆石化厂建设、铜陵有色金属厂的机械安装,宁国水泥厂上马等所需的重大件,都是在皖江航运的努力下得以顺利完成。通过长江连接近海、远洋运输,为安徽和世界交往搭起了一架海上之桥,对外贸易每年创汇1200多万美元。安徽境内江、河、湖沿岸的市镇农村,因为水运发达,货畅其流,促进了城乡经济的发展。 相似文献
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2011年末我国汽车保有量已超过1亿辆,其中商用车约占总保有量的23%,但其耗油量却达到汽车总耗油量的70%,成为汽车耗油的主力。2011年全年我国进口原油2 52亿t,全年原油产量2.01亿t,对外依存度超过55%,已进入了能源预警期。节能减排是缓解能源日趋紧张,促进行业持续健康发展的必由之路。在整个汽车领域,对于在汽车能源消耗中占绝对主导的商用车来说,减轻自重,降低油耗,对于我国交通运输的可持续发展来说更加迫切。汽车轻量化正是节约能源的最有效途径之一,在保证汽车的强度和安 相似文献