【作者】 董智； 马宗青； 刘永长；

【Author】 Dong Zhi;Ma Zongqing;Liu Yongchang;School of Materials Science and Engineering,Tianjin University;

【机构】 天津大学材料科学与工程学院；

【摘要】 与相应的合金基体相比,氧化物弥散强化(ODS)的合金具有显著提升的强度、组织稳定性和蠕变抵抗力,这使得它们在许多关键的领域具有很大的应用潜力。但由于添加的氧化物趋于在金属基体晶界处团聚长大,不能很好地弥散分布,这大大削弱了氧化物添加对合金的改善效果。基于此,我们以ODS-W合金为实验对象,首先结合水热和冷冻干燥法制备了具有钨包覆氧化物核壳结构的复合纳米粉末。在这种独特复合粉末中,纳米尺寸的氧化物(约2～5 nm)被均匀地包覆到钨晶粒内部,同时它们与周围的钨基体呈现出完全共格的界面特征。以该复合粉末为先驱粉,经低温烧结和高能锻加工以后,获得了强度和韧性匹配良好的ODS钨基合金。力学性能测试的结果表明:该ODS钨基合金在室温下延伸率为2.5%,抗拉强度为1390MPa,这表明该钨合金的韧脆转变温度降到了室温以下,打破了传统ODS-W合金在低温下呈脆性的局限性。600℃下强度为720MPa,延伸率为14%,具有优异的强韧性。综上,这种通过核壳结构前驱粉末来原位引入超细、共格的弥散强化相的方式能够显著改善合金的强韧性,并且有望应用于其他ODS合金体系。更多还原

【Abstract】 Compared with the corresponding alloy matrix,oxide dispersion strengthened(ODS) alloys have significantly improved strength,structure stability and creep resistance,which makes them have great application potential in many key areas.However,since the added oxide tends to agglomerate and grow at the grain boundary of the metal matrix,it cannot be dispersed well,which greatly weakens the improvement effect of the oxide addition on the alloy.Based on this,we took ODS-W alloy as the experimental object,and firstly combined hydrothermal and freeze-drying methods to prepare composite nanopowders with a core-shell structure of tungsten-coated oxide.In this unique composite powder,nano-sized oxides(approximately 2-5 nm) are uniformly coated inside the tungsten crystal grains,and at the same time they and the surrounding tungsten matrix exhibit completely coherent interface characteristics.Using the composite powder as the precursor powder,after low-temperature sintering and high-energy forging processing,an ODS tungsten-based alloy with well matched strength and toughness is obtained.The results of the mechanical properties test show that the elongation rate of the ODS tungsten alloy at room temperature is 2.5%,and the tensile strength is 1390 MPa,which indicates that the ductile brittle transition temperature of the tungsten alloy has dropped below room temperature,breaking the traditional ODS-W alloy.The limitation of brittleness at low temperature.The strength at 600℃ is 720 MPa,the elongation is 14%,and it has excellent strength and toughness.In summary,this method of introducing ultrafine and coherent dispersion strengthening phases in situ through the core-shell structure precursor powder can significantly improve the strength and toughness of the alloy,and is expected to be applied to other ODS alloy systems.更多还原