Zr基大块非晶中添加元素对非晶形成能力及耐蚀性的影响

Effects of additional element on the glass forming ability and corrosion resistance of bulk Zr-based amorphous alloys

运用实空间递归方法研究了添加元素Nb,Ta,Y,La对Zr基非晶合金的非晶形成能力和耐腐蚀性能的影响.用计算机编程构造了Zr基非晶中初始晶化相Zr2Ni的原子结构模型,用Zr2Ni中的二十面体原子团簇模拟非晶中的二十面体团簇.计算了替代二十面体中心或顶角位置原子前后Ni,Zr及合金元素的局域态密度、团簇中心Ni与近邻Zr原子及Ni与替代元素Nb,Ta,Y,La间的键级积分,还计算了合金元素替代前后团簇的费米能级.局域态密度计算结果表明:合金元素Cu占据二十面体团簇中心位置,Nb,Ta,Y,La占据二十面体团簇顶角位置.键级积分计算结果表明:合金元素取代Zr原子后,Y使非晶形成能力上升,Nb,Ta使非晶形成能力下降,La对非晶形成能力影响不大.费米能级计算结果表明:Nb,Y,La取代Zr使Zr基非晶容易钝化,提高了耐蚀性;Ta对Zr基非晶耐蚀性影响不大.综合合金元素对非晶形成能力和耐腐蚀性的影响,发现Y,La是最有益的合金元素,因此在Zr基非晶中通过加入少量的Y,La元素,可以制备出具有较高耐腐蚀性的大块非晶.

By using the real-place recursion method, bulk Zr-based amorphous alloys with effects of additional element Nb,Ta,Y, La on the glass forming ability and corrosion resistance were studied. The atomic structure model of primary precipitation phase Zr2 Ni in Zr-based amorphous alloys were constructed by computer programming. The icosahedron cluster in Zr-based amorphous alloys was simulated by using the icosahedral cluster in Zr2Ni primary precipitation phase. The local density of states （LDOS） curves of Zr, Ni （ before substitution） and alloying elements （after substitution） at the center or the corner of icosahedron cluster, the total bond order integral between the centered Ni atom and it＇s nearest neighbor （Zr, Nb, Ta, Y, La） in the icosahedron cluster, and the Fermi energy levels of the icosahedron cluster （before and after alloying elements＇ substitution） were calculated. The LDOS calculation results showed that the Cu atom occupies the center site of the icosahedral cluster, Nb, Ta, Y, La atoms occupy the site of Zr atom at the corner in Ni-Zr icosahedral clusters. The bond order integer calculation results suggest that Y increases the glass forming ability （GFA） of Zr-base amorphous alloys, Nb andTa decreased the GFA, and La has little influence on the GFA. The calculated Fermi energy levels suggest that Nb, Y, La make Zr-based amorphous alloys easy to be passivated and improve the Zr-based amorphous alloys corrosion resistance. Ta has little influence on the corrosion resistance of the alloys. Therefore, Y and La are most effective on improving the GFA and corrosion resistance of Zr-based amorphous alloys. By addition of small amounts of Y and La, new bulk amorphous alloys with good corrosion resistance can be prepared.