Mechanical Properties and Defect Evolution of Kr-Implanted 6H-SiC

摘要

Specimens of silicon carbide (6H-SiC) were irradiated with 5 MeV Kr ions (84Kr19+) for three fluences of 5× 1013,2×1014 and 1 ×1015 ions/cm2,and subsequently annealed at room temperature,500℃,700℃ and 1000℃,respectively.The strain of the specimens was investigated with high resolution XRD and different defect evolution processes are revealed.An interpretation of the defect evolution and migration is given to explain the strain variation.The mechanical properties of the specimens were studied by using a nano-indentation technique in continuous stiffness measurement (CSM) mode with a diamond Berkovich indenter.For specimens irradiated with fluences of 5× 1013 or 2× 1014 ions/cm2,hardness values exceed that of un-implanted SiC.However,hardness sharply degrades for specimens irradiated with the highest fluence of 1 ×1015 ions/cm2.The specimens with fluences of 5× 1013 and 2× 1014 ions/cm2 and subsequently annealed at 700℃ and 500℃,respectively,show the maximum hardness value.SiC is very suitable for use in advanced nuclear reactors and radioactive nuclear waste disposal due to its high-temperature stability,chemical inertness,good mechanical properties and small neutron capture cross sections.[1,2] The production of lattice damage and helium/heavier inert gas atoms due to irradiation and nuclear transmutation have been a serious concern for applications of silicon carbide in these environments.%Specimens of silicon carbide (6H-SiC) were irradiated with 5MeV Kr ions (84Kr19+) for three fluences of 5×1013, 2×1014 and 1×1015 ions/cm2, and subsequently annealed at room temperature, 500℃, 700℃ and 1000℃, respectively. The strain of the specimens was investigated with high resolution XRD and different defect evolution processes are revealed. An interpretation of the defect evolution and migration is given to explain the strain variation. The mechanical properties of the specimens were studied by using a nano-indentation technique in continuous stiffness measurement (CSM) mode with a diamond Berkovich indenter. For specimens irradiated with fluences of 5×1013 or 2× 1014 ions/cm2, hardness values exceed that of un-implanted SiC. However, hardness sharply degrades for specimens irradiated with the highest Huence of 1×1015 ions/cm2. The specimens with fluences of 5× 1013 and 2×1014 ions/cm2 and subsequently annealed at 700℃ and 500℃, respectively, show the maximum hardness value.