Ti对Zr-Nb二元合金β结构稳定性和力学性能的影响

Effect of Ti onβStructural Stability and Mechanical Properties of Zr-Nb Binary Alloys

利用团簇成分式方法设计了[Zr-Zr_(14)](Zr,Nb)3系列二元合金,进而采用Ti替代部分Zr形成三元合金;采用真空铜模吸铸快冷技术制备合金棒材,利用XRD、OM、TEM等对其进行微观组织表征和力学性能测试。结果表明,随着Nb含量增加,Zr-Nb二元合金基体结构从hcp-α向bcc-β转变,β结构稳定的同时伴随有ω相析出。适量Ti添加可显著抑制ω相的析出,进一步改善了合金的β结构稳定性。其中,单相bcc-β合金[Ti-Zr_(14)]Nb3(Zr-17.37Nb-2.98Ti,质量分数,%)表现出低弹性模量(E=57 GPa)的同时具有最佳的力学性能(屈服强度σYS=557 MPa、延伸率δ=15.5%)。

Metastable bccβ-Zr alloys generally have low elastic modulus,magnetic susceptibility,good mechanical properties,corrosion resistance,and biocompatibility,which are ascribed to co-alloying of multiple elements to enhance the structural stability of the bcc-βphase.This work systematically investigated the effects of Nb and Ti elements on the structural stability of the bcc-βphase and mechanical properties of Zr-Nb-Ti alloys.Various binary[Zr-Zr_(14)](Zr,Nb)3 alloy compositions were designed by the cluster formula approach,based on which Ti was substituted for the base Zr to form ternary alloys.Alloy rods were prepared by the copper-mold suction-cast method with vacuum protection.The microstructure and mechanical properties of the alloys were characterized using XRD,OM,and TEM etc.The results show that the crystal structures of the Zr-Nb binary alloys could change from hcp-αto bcc-βwith increasing Nb content,whereas,theω-phase always coexists with theβ-phase.An appropriate amount of Ti addition can significantly inhibit the precipitation ofω,resulting in the further improvement of the stability of theβ-phase.The singleβ-[Ti-Zr_(14)]Nb3(Zr-17.37Nb-2.98Ti,mass fraction,%)ternary alloy exhibited not only a low elastic modulus of E=57 GPa but also a good tensile property with a high yield strength ofσYS=557 MPa and an elongation ofδ=15.5%.