Vanadium alloy of fast neutron absorption cross section is small, the liquid metal lithium, sodium, potassium, etc. With good corrosion resistance, and good strength and plasticity, good processability, and can resist radiation embrittlement, radiation-hardened swelling, under the irradiation has good dimensional stability, is an important reactor structural materials. Typical vanadium alloys include v-15ti-7.5 Ct, v-15cr-5ti, v-10ti, v-20ti, v-9cr-3fe-1.5 zr-0.05 C. These vanadium alloys are used as fuel sheaths and structural elements for liquid metal cooled fast neutron breeder reactors. Other Vanstar7(v-9cr-3fe-zrc), Vanstar8(v-9cr-3ta-zrc), Vanstar9(v-6fe-3nb-zrc), v-40nb-1.3 Zr, v-9cr-10w-1.5 Zr, v-9cr-10ta-1.25 Zr, etc.
Vanadium - based alloy, as a candidate structural material of the convertor reactor, was first introduced to V24Cr24Ti. It is a typical low active material, can be used to ~ 700 ℃ high temperature area and keep the enough strength and good high temperature creep resistance. At high temperature, the interstitial impurity atoms of C, N and O in the alloy interact strongly with Ti, forming Ti2CON precipitation phase, which affects the performance of the alloy. Of the existing research results show that for V24Cr24Ti alloy solid solution treatment in ~ 700 ℃ annealing form highly dispersed distribution of small precipitation phase, to strengthen the alloy at the same time, reduce the plastic alloy. However, the research results of niura shimura et al show that the plastic reduction of the alloy is not large and should be within the acceptable range of engineering application. Therefore, precipitation hardening appears to be used to obtain higher strength V24Cr24Ti alloys to reduce the weight of vanadium alloy components and reduce manufacturing costs. The existing research results have been found in the short-term (1 h) annealing of the alloy, and the potentiality of the long-term high temperature aging treatment has been rarely reported. The aging strengthening of V24Cr24Ti, V26W21Ti and V26W24Ti alloys was studied by tensile test and hardness test.
Pure metal is used to smelt alloy in maglev furnace. The purity of other raw materials is greater than 99.5%. Raw materials are evenly mixed, and cold pressing into Φ 50 mm spindle, into the magnetic suspension in the water cooled copper crucible furnace. Under the heating of high frequency induction current, the spindle melts quickly from the surface to the inside, and is further homogenized under the stirring of magnetic force. Ar gas is used to protect the alloy from oxidation. Each spindle is smelted 3 times to ensure uniform alloy composition. Alloy ingot after forging breakdown, hot-rolled and cold-rolled, become 0. 5 ~ 1 mm sheet, and finally 1 h under 1100 ℃ vacuum annealing, vacuum degree is better than that of 4 x 10-4 Pa, with even the recrystallization organization. Forging temperature 950 ~ 1150 ℃, hot rolling temperature 850 ℃. All heat treatment is carried out in the air. In order to prevent the alloy from absorbing oxygen, nitrogen and other impurities from the air, surface coating and copper sheath are adopted.
