J. Mater. Sci. Technol. ›› 2019, Vol. 35 ›› Issue (5): 930-938.DOI: 10.1016/j.jmst.2018.11.004

• Orginal Article • Previous Articles     Next Articles

Formation of coherent, core-shelled nano-particles in dilute Al-Sc-Zr alloys from the first-principles

Chaomin Zhangab, Yong Jiangabc?(), Fuhua Caoa, Tao Huac, Yiren Wanga, Dengfeng Yinab?()   

  1. aKey Laboratory of Nonferrous Materials of the Chinese Ministry of Education, School of Materials Science and Engineering, Central South University,Changsha 410083, China
    bDepartment of Mathematical and Physical Education, Yantai Nanshan University, Yantai 265713, China
    cState Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China
  • Received:2018-06-10 Accepted:2018-08-12 Online:2019-05-10 Published:2019-02-20
  • Contact: Jiang Yong,Yin Dengfeng
  • About author:

    1 These authors contribute equally to this paper.

Abstract:

We present a systematic first-principles based study on the formation of coherent L12-phase nano-particles in dilute Al-Sc-Zr alloys. Bulk structures and properties, solute substitution, interface formation energies, and interfacial coherent strains are all calculated. Nucleation modeling and relevant energetic calculations are performed on various possible structures of L12-phase nano-precipitates, i.e. individual L12-Al3Sc and L12-Al3Zr, homogeneous L12-Al3(ScxZr1-x) and the core-shelled L12-Al3Sc(Al3Zr) and L12-Al3Zr(Al3Sc). The following insights are obtained. Matrix-dissolved Sc or Zr strongly prefers to substitute the X sublattice sites in L12-Al3X (X = Zr or Sc), while the inter-substitution between L12-Al3Sc and Al3Zr is only weakly feasible. The cube-on-cube orientation with the (100)/(100) contacting facets is the most energy favored for the Al/Al3Sc(L12), Al/Al3Zr(L12) and Al3Sc (L12)/Al3Zr(L12) interfaces. All these interfaces are highly coherent, with fairly low formation energy. And particularly, the Al3Sc(L12)/Al3Zr(L12) interface has essentially zero formation energy. Ternary L12-Al3(ScxZr1-x) precipitates tend to form a Al3Sc-based core and Al3Zr-based shell structure, with a relatively sharp inner interface of Al3Sc(L12)/Al3Zr(L12). This core-shelled structure becomes energetically more favorable for the particle size R > 1-2 nm. The potential influence of the Sc/Zr ratio and temperature on the relative stabilities of L12-phases in Al is also evaluated and discussed.

Key words: Al-Sc-Zr, Precipitation, Interface, Core-shell structure, First principles