Further mechanism of α/β interphase boundary evolution and dynamic globularization of Ti–5Al–2Sn–2Zr–4Mo–4Cr at elevated temperature deformation

The evolution characterization of the α/β interphase boundaries of the isothermally compressed Ti–5Al–2Sn–2Zr–4Mo–4Cr with lamellar microstructure was carried out via electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The effect of the α/β interphase boundary evolution on the dynamic globularization was discussed, and the nucleation model for the β recrystallized grain at the cusp of α lath in the late stage of deformation in terms of the classic nucleation theory was established. The mean α/β interface deviation angle from Burgers orientation relationship (BOR) increased continuously up to 18.9° with the increasing strain from 0.1 to 0.5, which was dominated by the continuous dynamic recrystallization. Restoration of BOR between α and β phases at the strains of 0.7 and 0.9 occurred due to the occurrence of recrystallized α and β grains following BOR, which was rationalized by a nucleation model considering the stored energy of deformation provided the driving force for nucleation at the cusp of α lath. Loss of coherency of α/β interphase boundaries at a strain about 0.3 was responsible for accelerating the dynamic globularization of α lamellae since the energy of α/β interphase boundaries increased up to the maximum value when the non-coherent α/β interphase boundaries were formed. Restoration of coherency of α/β interphase boundaries due to the recrystallization nucleation in the late stage of deformation did not substantially affect the dynamic globularization since the α/α intraphase high-angle boundaries (HAGBs) were formed and the most α/β interphase boundaries were non-coherent.     

Zr对Al-10Zn-2.5Mg-1.6Cu合金板材组织与性能的影响

针对T6态Al-10Zn-2.5Mg-1.6Cu铝合金板材，研究了添加质量分数分别为0，0.046%，0.098%，0.151%，0.185%的Zr，铝板中合金相粒子和晶粒的组态以及板材的力学性能.结果表明，Zr含量增加对铝板中微米级T相和Al₇Cu₂Fe相粒子无明显影响，合金中未形成含Zr的结晶相，但纳米级Al₃Zr弥散相粒子数量逐渐增多.添加质量分数为0.046% Zr可细化T6态铝板等轴状Cube取向晶粒；Zr质量分数超过0.098%能抑制铝板再结晶形核，板材晶粒为纤维状，取向以Brass，S，R和Copper为主，且其体积分数随Zr含量增加而逐渐增大.Zr含量增加，T6态铝板的强度逐渐增大，而延伸率先增大后略有减小.Zr质量分数为0.151%的T6态Al-10Zn-2.5Mg-1.6Cu铝合金板材性能最佳，其抗拉强度、屈服强度和延伸率分别为706，645MPa和10.3%.