稀土Y元素对CuAlMn形状记忆合金晶粒细化及其力学性能的影响
Effect of rare earth Y element on grain refinement and mechanical properties of Cu AlMn shape memory alloys
千佳祥 1杨院霞 1张江 1郝刚领 1王幸福 2王新福 1王伟国 1李先雨 1许巧平1
作者信息
- 1. 延安大学 物理与电子信息学院,陕西 延安 716000
- 2. 中国科学院固体物理研究所 材料物理重点实验室,合肥 230031
- 折叠
摘要
CuAlMn形状记忆合金具有优良的耐热稳定性和高阻尼特性,在多种领域有着明确的目标需求,然而,晶粒粗大易导致沿晶断裂,严重弱化了合金的力学性能.为改善合金力学性能,引入了稀土Y元素,采用电弧熔炼吸铸炉制备了Cu-11.36Al-5Mn-x Y(x=0～3,质量分数/%,下同)系列铸态合金,又经固溶时效对合金微观组织进行了调控和均质化.采用DSC、XRD、金相和SEM对合金的相变、物相、微观组织结构进行了表征.通过显微硬度计和万能材料试验机测试了合金的硬度和力学性能.结果表明,Y元素添加可有效细化CuAlMn合金晶粒,晶粒尺寸从数百微米下降至10 μm左右,同时伴随着大量网格状含Y析出相沿晶析出,冷却过程中晶粒形核区的增多和生长受到抑制是晶粒细化的主要因素.合金硬度随Y元素添加量的增大而升高,这与合金中大量含Y硬脆相的析出有关,Y含量越高,析出相体积分数越高,此外,固溶时效态样品硬度高于铸态样品,源于固溶时效态样品析出相在整个基体内的分布和更高的析出相体积分数.合金的压缩强度和拉伸断裂强度在Y元素含量为0.1%～0.4%时得到明显提升,其强化机制可通过细晶强化、沉淀强化和固溶强化来理解.合金压缩断裂应变在Y元素含量为0.4%时达到最大,断后伸长率在Y元素含量为0.1%时达到最大,其变化趋势与晶粒细化和沉淀析出相的耦合效应有关.
Abstract
CuAlMn shape memory alloys have specific target demands in various fields due to excellent thermal stability and high damping properties.However,the mechanical property of the alloy is severely weakened due to the intergranular fracture arising from the coarse grain size.To improve the mechanical properties,the Cu-11.36Al-5Mn-x Y(x=0-3,mass fraction/%,the same below)alloys were prepared by using a vacuum arc melting furnace by introducing rare earth Y element.The microstructure of the as-cast CuAlMn alloy was subsequently tailored and homogenized through solid solution and aging treatment.The phase transformation,phase composition,and microstructure of the alloy were respectively characterized by DSC,XRD,metallography and SEM observations.The hardness and mechanical properties of the alloy were tested by using a microhardness tester and a universal materials testing machine.Results show that the addition of Y element effectively refines the CuAlMn alloy grain,and the grain size even reduces from several hundred μm to around 10 μm.The grain refinement is mainly associated with the increased grain nucleation areas and the inhibition of grain growth during the cooling process.Moreover,quite numbers of Y-containing precipitates with the network structure are formed and distributed along the grain boundaries.The hardness of the alloy increases with the enhancement of Y element addition,which is associated with the precipitation of a large amount of hard and brittle containing Y phases.The hardness of the solution-aged sample is higher than that of the cast sample,due to the precipitate distribution throughout the entire matrix and higher volume fraction of precipitates for the former sample.In addition,the compressive and tensile fracture strength of the alloy are significantly improved when the Y content is in the range of 0.1%-0.4%.The strengthening mechanism can be understood by grain refinement strengthening,precipitation strengthening and solution strengthening.The compressive fracture strain of the alloy reaches its maximum when the Y content is 0.4%,while the elongation after fracture exhibits the maximum value with Y content of 0.1%.The changing trend is closely related to the coupling effect between grain refinement and precipitation phases.
关键词
CuAlMn形状记忆合金/稀土Y元素添加/晶粒细化/力学性能Key words
CuAlMn shape memory alloy/rare earth Y element addition/grain refinement/mechanical property引用本文复制引用
基金项目
国家自然科学基金资助项目(52061038)
国家自然科学基金资助项目(51661032)
国家自然科学基金资助项目(51301150)
陕西省特支计划区域发展人才专(2020-44)
陕西省青年科技新星资助项目(2013KJXX-11)
出版年
2024
国家科技期刊平台
NSTL
万方数据