稀土元素Sc、Nd对Al-Mg合金显微组织及力学性能影响

【作者】 詹传明；

【导师】 刘楚明； 江国金；

【作者基本信息】 中南大学 ， 材料加工工程， 2008， 硕士

【摘要】 通过室温拉伸性能测试、显微硬度测试、电导率测试、金相显微分析、扫描电镜及透射电镜观察等手段,研究了微量稀土钪（Sc）和钕（Nd）对Al-Mg合金的组织（铸态、均匀化态、热轧态、冷轧态、退火态）与性能（力学性能、导电性）的影响,并从理论上进行了分析和讨论。研究结果表明:1.单独加入稀土Sc、Nd和复合加入Sc、Nd均能不同程度地提高Al-Mg合金的冷轧态的抗拉强度。单独添加0.2%Nd,可使合金抗拉强度提高14MPa,单独添加0.2%Sc合金抗拉强度的提高29MPa,以复合形式添加0.2%Nd和0.2%Sc时合金抗拉强度提高55MPa。2.在Al-Mg合金中添加Sc和Nd可以细化合金的铸态组织,其中单独添加Sc的细化作用比单独添加Nd强,而Sc和Nd以复合形式加入时的细化效果最好。3.在Al-Mg合金中单独添加Nd对合金的再结晶行为影响不大;单独添加Sc以及同时添加Nd和Sc时合金的再结晶温度提高40℃。4.在Al-Mg-Nd-Sc合金中,析出相Al₃（Sc,Nd）粒子为细小、弥散的纳米级粒子,对晶界的钉扎作用导致合金再结晶温度升高。5.复合加入Sc和Nd对合金再结晶抑制作用最显著,这就使第二相粒子得到充分析出,从而使其电导率的峰值最高。更多还原

【Abstract】 Using tensile test at room temperature, hardness measurement, electrical resistance test at room temperature, optical microscopy（OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, the mechanical and electric properties and the microstructure of Al-Mg alloys at the state of casting, homogenization, hot-rolling,cold-rolling and annealling were studied. These were also analysed and explained in theory. The results show that:The first, the addition of minor Sc and Nd respectively or meanwhile can lead to increase the level of Al-Mg alloy tensile strength at the state of cold-rolling. The tensile strength of the cold-rolled alloy is improved by 14 Mpa when adding respectively 0.2%Nd, by 29 Mpa when adding respectively 0.2%Sc, and by 55 Mpa when adding meanwhile 0.2%Nd and 0.2%Sc.The second, the addition of minor Sc and Nd leads to refine the grain of as-cast microstructure in Al-Mg alloys. The fine grains in the alloys added Sc are better than ones in the alloys added Nd. The effect of refinement when adding Sc and Nd with a compound form are best.The third, the alloys recrystallization behavior when just addingNd is not very obviously inhibited. Addding Sc respectively or adding compositely Sc and Nd will inhibit recrystallization, and the recrystallization temperature is improved by 40℃.The fourth, in Al-Mg-Sc-Nd alloy, precipitates Al₃（Sc, Nd） as refined particles and nano-disperesed ones, they play a dominant role on pinning the grain boundary, leading to improve the recrystallization temperature.The fifth, the recrystallization was evidently restrained when adding Sc and Nd with a compound form. So these make the second-phase precipitated enough, and make peak values of specific conductance to the top.更多还原