中文摘要：

将再结晶退火后的Zr-0.72Sn-0.32Fe-0.15Cr-0.97Nb合金在300℃,8 MPa去离子水的高压釜中短时腐蚀,用TEM,EDS和SEM研究了合金中的第二相及其腐蚀行为.结果表明,第二相的尺寸主要分布在30~100 nm,最大尺寸为230 nm.第二相成分中的Nb/Zr比（原子比）与其尺寸大小和晶体结构有一定的相关性,当Nb/Zr=0时,第二相粒子尺寸大于150 nm;当0.100.75时,第二相粒子尺寸小于30 nm.第二相的腐蚀行为与其成分密切相关,Nb/Zr比大于0.5时,第二相更容易被腐蚀,并形成非晶氧化物.

英文摘要：

Zr-0.72Sn-0.32Fe-0.15 Cr alloy, which has much better corrosion resistance than that of Zr-4 alloy, was alloying by adding 1%Nb（mass fraction）. In order to understand the effect of Nb on the corrosion resistance of Zr-0.72Sn-0.32Fe-0.15 Cr alloy, the second phase particles（SPPs） and their oxidation behavior in this alloy were investigated using TEM, SEM and EDS techniques. Thin foil specimens for TEM observation were prepared for Zr-0.72Sn-0.32Fe-0.15Cr-0.97 Nb alloy after recrystallization annealing. The corrosion tests for these thin foil specimens were conducted in an autoclave at 300 ℃, 8 MPa in deionized water for short time exposure. The results showed that a thin oxide layer in several hundred nanometers mainly consisted of the monoclinic Zr O2 formed on the surface, and SPPs embedded in the thin foil specimens at different corrosion levels were observed after corrosion test. The sizes of SPPs were mainly distributed between 30~150 nm and the maximum size was 230 nm. The size and crystal structure of SPPs have a relationship with Nb/Zr ratio（atomic ratio） of their composition. When Nb/Zr ratio was about zero, the size of SPPs was over 150 nm. When Nb/Zr ratio was in the range of 0.10~0.50,the sizes of SPPs were between 60~150 nm. When Nb/Zr ratio were in the range of 0.50~0.75, the sizes of SPPs were between 30~60 nm. When Nb/Zr ratio was over 0.75, the size of SPPs was smaller than 30 nm. With the increase of Nb/Zr ratio of their composition, three kinds crystal structure of Nb-containing SPPs, fcc（lattice constant a=0.701 nm）, hcp（lattice constants a=0.508 nm, c=0.832 nm） and bcc（a=0.325 nm） structures were detected.SPPs without Nb containing have fcc structure（a=0.817 nm） while Fe/Cr ratio was over 5.00 and hcp structure（a=0.492 nm, c=0.788 nm） while Fe/Cr ratio was less than 3.00. The oxidation behavior of SPPs also had a relationship with the Nb/Zr ratio. The SPPs were easy to be oxidized to amorphous when Nb/Zr ratio was over 0.50. However, the SPPs with Nb/Zr ratio