摘要
L1_(2)-Al_(3)Sc纳米析出相的热稳定性对于Al-Sc合金的耐热性意义重大.不同溶质原子在L1_(2)-Al_(3)Sc界面的偏析行为可能对Al-Sc合金中L1_(2)-Al_(3)Sc析出相的热稳定性造成影响.本文针对过渡族微合金化元素Cu和Ti的L1_(2)-Al_(3)Sc/Al界面偏析,开展第一性原理能量学计算研究.结果表明,Cu和Ti均倾向于以替换方式偏析在界面Al侧,但偏析驱动力和偏析占位有明显差异.在给定温度下,基体浓度对界面偏析量也有重要影响.基体浓度越高,偏析驱动力越大,界面平衡偏析量或最大界面覆盖率越大.温度为600 K、基体原子浓度为1%时,Ti对偏析界面的最大覆盖率可达80%(0.8单原子层),而Cu不超过4%(0.04单原子层).
Thermal stabilities of L1_(2)-Al_(3)Sc nano-precipitates are critical for the thermotolerance of Al-Sc based alloys.Previous experiments have suggested that different alloying elements may have different segregation behaviors at the L1_(2)-Al_(3)Sc/Al interface,which can exert different influences on the thermal stability of L1_(2)-Al_(3)Sc nano-precipitates.To clarify the responsible mechanism from a quantitative approach,first-principles calculations of energetics are performed in this work,to investigate the segregation behaviors of transition-metal elements Cu and Ti at the L1_(2)-Al_(3)Sc/Al interface.The results suggest that both Cu and Ti can segregate to the interface,and substitute Al or Sc sites on its Al side with different thermodynamic driving forces.Given a temperature,segregation amount is largely determined by the initial elemental concentration in the Al matrix.The higher the segregation driving force and the initial matrix concentration are,the higher the equilibrium segregation amount(or the maximum interfacial coverage)could be.With an initial matrix atomic concentration of 1%,the maximum interfacial coverage of Ti can reach up to 80%(0.8 monolayer layer(ML))while that of Cu is less than 4%(0.04 ML)at T=600 K.
作者
姚建刚
宫裕祥
江勇
Yao Jian-Gang;Gong Yu-Xiang;Jiang Yong(School of Materials Science and Engineering,Yantai Nanshan University,Yantai 265713,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第8期312-318,共7页
Acta Physica Sinica
基金
国家自然科学基金(批准号:51971249)
山东省自然科学基金(重点项目)(批准号:ZR2020KE012)资助的课题~~。
