热加工对Zr-Sn-Nb合金显微组织的影响研究

Effects of Thermo-mechanical Processing on Microstructure of Zr-Sn-Nb Alloy

对Zr-Sn-Nb合金在4种温度(750℃、780℃、800℃和820℃)下进行了热/冷加工和最终再结晶退火,并对在上述4种温度下加热的试样进行了淬火处理。用透射电子显微镜(TEM)和光学金相显微镜(OM)研究了试样的显微组织、β-Zr以及第二相粒子的特征。结果表明,当加热温度达到780℃或高于此温度时,Zr-Sn-Nb合金已进入α+β双相区;随着加热温度的增加,β-Zr相含量增多;加工后试样中的第二相粒子大部分为C14型六方结构的Zr(Fe、Cr)2Laves相,与Zr-4合金中第二相结构相同,点阵常数a=0.502nm、c=0.818nm。同时,还发现有少量C15型面心立方结构Zr(Fe、Cr)2Laves相,点阵常数a=0.716nm。

Hot-rolling, cold-rolling and quenching tests of Zr-Sn-Nb alloy were carried out at 750°C, 780°C, 800°C and 820°C, respectively. The microstructures of different heat-treated Zr-Sn-Nb alloy and the characteristics of P-Zr and second precipitate particles were studied and analyzed using transmission electron microscope (TEM) and optical microscope (OM). The results showed that N18 contained α+β phases while heating at 780°C and above, and the higher the heating temperature, the more the P-Zr phases produced. The majority of second phase particles (SPPs) in Zr-Sn-Nb alloy were h.c.p Zr(Fe, Cr)2 Laves phases with the lattice parameter a=0.502 nm, c=0.818 nm, which was similar to that of Zr-4 alloy. In addition, there were a few f.c.c. Zr(Fe, Cr)2 Laves phases with lattice parameter a=0.716 nm. The results have been discussed extensively.