Nb、Ta等元素对Zr基大块非晶形成能力及耐腐蚀性影响机理研究

INFLUENCE OF Nb,Ta AND OTHER ELEMENTS ON GLASS FORMING ABILITY AND CORROSION RESISTANCE OF Zr-BASED AMOPHOUS ALLOY

用计算机编程构造了Zr基非晶合金包含二十面体原子团簇的Zr2Ni晶体相.用Zr2Ni晶体相中以Ni原子为中心的二十面体原子团簇模拟Zr基非晶中二十面体团簇.应用实空间的递归方法计算了合金元素取代二十面体原子团簇中心和顶角位置原子时的局域态密度、二十面体原子团簇中中心Ni原子与其近邻合金元素Nb、Ta、Ti、V的总键级积分及团簇的费米能级.结果表明,Nb、Ta、Ti和V取代Zr原子后使其与Ni的键级积分有所降低,使合金的非晶形成能力下降,但Nb、Ta对合金的非晶形成能力影响不大;Nb、V取代Zr使费米能级升高,可使Zr基非晶容易钝化,提高耐蚀性;Ta对Zr基非晶的耐蚀性影响不大.而Ti使Zr基非晶的钝化能力下降.综合合金元素对非晶形成能力和耐腐蚀性的影响,Nb是最有益的合金元素,即在Zr基非晶中,通过加入少量的Nb元素,可以制备出具有较高耐腐蚀性的大块非晶.

The atomic structure model of phase Zr2Ni containing icosahedron cluster in Zr-based amor- phous alloys were constructed by computer programming. The icosabedron cluster in Zr-based amorphous alloys was simulated by using the icosahedral cluster with a Ni atom at the center and 12 Zr（ or partly replaced by Nb, Ta , Ti, V ） atoms as nearest neighbors in Zr2 Ni primary precipitatiion phase. The LDOS curves of alloying element which substituted the atoms at the center or at the corner of icosahedron cluster, the total bond order integral（ ∑ BOI） between the center Ni atom and its neighbor （ Zr, Nb, Ta, Ti, V） in the icosahedron cluster, and the Fermi levels of the icosahedron cluster containing alloying elements were calculated. The results showed that the ∑ BOI is decreased by Nb, Ta, Ti, V substituting Zr, which reduces the glass forming ability of Zr-based amorphous alloys, but Nb, Ta has little influence on the GFA of the alloys. The Fermi levels of icosahedron cluster go up by Nb, V substituting Zr, which suggests that Nb, V enables Zr-based amorphous easy to passive and improves its corrosion resistance. The case of Ta is near to the Zr＇s, so Ta has little influence on the corrosion resistance of the alloys. Ti reduces the passivation ability of the Zr-base amorphous alloys. Therefore, Nb are effective for enhancing the glass forming ability and corrosion resistance of Zr-based amorphous alloys. By addition of minor Nb, the new bulk Zr- based amorphous allovs with good corrosion resistance may be prepared.