Effect Of Al On The Mechanical And Thermal Properties Of Fe-13Cr-(2～6)Al Core Clad Materials

Since the occurrence of a nuclear leak at the Fukushima Nuclear Power Plant in Japan in 2011,the concept of"accident fault-tolerant fuel"has been proposed,and the development of new accident-tolerant fuel cladding materials has been listed as one of the development plans.Fe-Cr-Al cladding materials are considered to be one of the candidate materials for nuclear fuel cladding materials of new generation nuclear energy systems with their known good high-temperature strength and high-temperature oxidation resistance,and have high research value.In this study,five groups of Fe-Cr-Al alloy ingots with Cr content of 13 wt.%and Al content of 2wt.%,3wt.%,4wt.%,5wt.%and 6wt.%were prepared from high purity Fe ingots,Cr blocks and Al granules.The ingots were homogenized and heat-treated at 1150℃ for 3h,then rolled into 16mm thick plates at 800℃ and sampled for recrystallization annealing at 1000℃ for 10 min to obtain Fe-Cr-Al alloy samples.The mechanical properties and thermal properties of Fe-Cr-Al alloy were studied.The cladding tube has been used in high temperature,high pressure and high corrosive environment for a long time.The Fe-Cr-Al core cladding material needs sufficient mechanical properties to maintain the overall shape of the cladding tube.It also needs good thermal properties to ensure the nuclear energy system Life,safety and energy conversion efficiency.The Al content will greatly affect the mechanical and thermal properties of Fe-Cr-Al core cladding materials.Therefore,with the high-purity Fe,Cr,and Al as raw materials,the Cr content is designed to be 13 wt.%,And the Al content is 2 wt.%,3 wt.%,4 wt.%,5 wt.%,And 6 wt.%.Preparation scheme of 5 groups of Fe-Cr-Al alloy ingots.In the study,5 groups of ingots were homogenized and heat-treated at 1150℃ for 3 hours,and then rolled into a 16mm thick plate at 800℃ and sampled for recrystallization annealing at 1000℃ for 10 minutes to obtain Fe-Cr-Al alloy samples.The mechanical and thermal properties of the alloy were tested,and the effects of Al on the mechanical and thermal properties of Fe-Cr-Al alloys were studied.The study found that in the Fe-13Cr-(2～6)Al alloy system,the alloys are all pure ferrite alloys,and theα-Fe single-phase structure does not change with the change in Al content,but its lattice constant,hardness,and yield strength increases exponentially with increasing Al content.Fe-13Cr-6Al has the largest Rockwell hardness and compressive yield strength,reaching 23.8HRC and 384Mpa,respectively.When the Al content gradually increases,the thermal conductivity and thermal diffusion coefficient of the Fe-Cr-Al alloy gradually decrease,and the specific heat capacity is almost unchanged.At room temperature,the thermal conductivity and thermal diffusion coefficient of Fe-13Cr-2Al are the largest,reaching 19.7 W/(m·K)and 5.8 mm~2/s,respectively.At 350℃,the thermal conductivity and thermal diffusion coefficient of Fe-13Cr-2Al are the largest,reaching 23.6 W/(m·K)and 5.2 mm~2/s,respectively.The specific heat capacity is about 0.46 J/(g·K)and about 0.62 J/(g·K)at room temperature and 350℃ respectively.The theoretical thermal conductivity is obtained by superposing the calculation results of the electronic and phonon thermal conductivity.The maximum thermal conductivities at 350℃ were 22.1W/(m·K)and 25.5W/(m·K),which were in good agreement with the experimental values,and the model had certain reliability.