HEAT TREATMENT, TENSILE PROPERTIES, AND CORROSION RESISTANCE OF Zr-2 a/o Nb-2 a/o Sn ALLOY

摘要

Zr-2a/o Nb-2a/o Sn alloy is heat treatable in the temperature range commonly used in the beta treatment given uranium fuel elements. The heat treatability of zirconium base alloys is generally attributed to the formation of a martensite upon quenching from the beta or beta plus alpha zirconium range. This hardening mechanism must be rejected for the Zr-2a/o Nb-2a/o Sn alloy as quench hardening occurs at temperatures below which beta zirconium does not exist.nThe strength of the alloy is from 50 per cent to 150 per cent greater than Zircaloy-2 when quenched from temperatures in the 660 C to 780 C range. Material quenched from above 780 C gives only slight improvements in strength over the material quenched from 780 C while that quenched below 660 C gives only slight increases in strength above annealed material. On the basis of strength and ductility, Zr-2a/o Nb-2a/o Sn alloy would be superior to Zircaloy-2 in cladding applications. The corrosion resistance is so poor, however, as to eliminate its candidacy as a fuel element cladding material.