Brazeability evaluation of Ti-Zr-Cu-Ni-Co-Mo filler for vacuum brazing TiAl-based alloy

Ti-47Al-2Nb-2Cr-0.15B(mole fraction,%)alloy was vacuum brazed with amorphous and crystalline Ti.25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(mass fraction,%)filler alloys,and the melting,spreading and gap filling behaviors of the amorphous and crystalline filler alloys as well as the joints brazed with them were investigated in details.Results showed that the amorphous filler alloy possessed narrower melting temperature interval,lower liquidus temperature and melting active energy compared with the crystalline filler alloy,and it also exhibited better brazeability on the surface of the Ti.47Al.2Nb.2Cr.0.15B alloy.The TiAl joints brazed with crystalline and amorphous filler alloys were composed of two interfacial reaction layers and a central brazed layer.Under the same conditions,the tensile strength of the joint brazed with the amorphous filler alloy was always higher than that with the crystalline filler alloy.The maxmium tensile strength of the joint brazed at 1273 K with the amorphous filler alloy reached 254 MPa.

Co-Ti合金中γ相粗化动力学的实验研究和相场模拟（英文）

本研究结合实验和相场法研究了反相Co-19.7Ti合金中无序γ析出相的组织演变和粗化行为。实验和模拟结果皆表明γ相的形貌随时效时间增加由近球形转变成条状。γ相平均粒径的粗化动力学遵循r^3=kt,可获得如下■texp[-349890RT]。γ相平均粒径随时效时间的变化分为两个阶段,阶段I增长快速而阶段II增长速度减缓。时效温度由700℃增至750℃,γ相粒径分布的峰值变大以及粒径分布的宽度变窄,模拟结果与实验结果取得良好的一致性。