Molecular dynamics simulations are used to investigate the stabilities of C15 Laves phase structures subjected to temperature and point defects. The simulations based on different empirical potentials show that the bu...Molecular dynamics simulations are used to investigate the stabilities of C15 Laves phase structures subjected to temperature and point defects. The simulations based on different empirical potentials show that the bulk perfect C15 Laves phase appears to be stable under a critical temperature in a range from 350 K to 450 K, beyond which it becomes disordered and experiences an abrupt decrement of elastic modulus. In the presence of both vacancy and self-interstitial, the bulk C15 Laves phase becomes unstable at room temperature and prefers to transform into an imperfect body centered cubic（BCC）structure containing free vacancies or vacancy clusters. When a C15 cluster is embedded in BCC iron, the annihilation of interstitials occurs due to the presence of the vacancy, while it exhibits a phase transformation into a（1/2） 111 dislocation loop due to the presence of the self-interstitial.展开更多
The Ni–Fe–Cr based superalloy with percentage additions of Nb,Al and Ti,called"Inconel X750 superalloy",is studied with its importance in nuclear application.Under reactor neutron irradiation,the strengthe...The Ni–Fe–Cr based superalloy with percentage additions of Nb,Al and Ti,called"Inconel X750 superalloy",is studied with its importance in nuclear application.Under reactor neutron irradiation,the strengthening phase Ni3(Al,Ti)in the form of gamma prime precipitates were somehow disordered,and dissolved eventually,by which the mechanical properties of materials were degraded.It is of high interests to investigate the e ects of transmutation production helium on radiationinduced instability of gamma prime in the materials.The transmission electron microscope in situ heavy ion irradiations with and without pre-injected helium are performed purposely.The precipitates were disordered by heavy ion irradiation after 0.06 displacement per atom(dpa).The presence of 2×10-4 atoms helium delayed the disordering of Ni3(Al,Ti)precipitates to 0.68 dpa.With 4×10-4 atoms helium,the precipitates required doses of>2.7 dpa to become disordered.In addition,the precipitation of M23C6 particles were observed at 600℃irradiation to 5.4 dpa with 4×10-4 atoms helium pre-injected.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11675230 and 11375242)Canada’s Natural Sciences and Engineering Research Council NSERC Discovery GrantCanada Foundation for Innovation CFI
文摘Molecular dynamics simulations are used to investigate the stabilities of C15 Laves phase structures subjected to temperature and point defects. The simulations based on different empirical potentials show that the bulk perfect C15 Laves phase appears to be stable under a critical temperature in a range from 350 K to 450 K, beyond which it becomes disordered and experiences an abrupt decrement of elastic modulus. In the presence of both vacancy and self-interstitial, the bulk C15 Laves phase becomes unstable at room temperature and prefers to transform into an imperfect body centered cubic（BCC）structure containing free vacancies or vacancy clusters. When a C15 cluster is embedded in BCC iron, the annihilation of interstitials occurs due to the presence of the vacancy, while it exhibits a phase transformation into a（1/2） 111 dislocation loop due to the presence of the self-interstitial.
基金financially supported by National Science and Engineering Research Council(NSERC-CRDs with Grant Nos.CRDPJ 442006-2012 and CRDPJ/532182-2018)benefited from the use of electron microscopy at the RMTL facility,constructed with funding from CFI/ORF
文摘The Ni–Fe–Cr based superalloy with percentage additions of Nb,Al and Ti,called"Inconel X750 superalloy",is studied with its importance in nuclear application.Under reactor neutron irradiation,the strengthening phase Ni3(Al,Ti)in the form of gamma prime precipitates were somehow disordered,and dissolved eventually,by which the mechanical properties of materials were degraded.It is of high interests to investigate the e ects of transmutation production helium on radiationinduced instability of gamma prime in the materials.The transmission electron microscope in situ heavy ion irradiations with and without pre-injected helium are performed purposely.The precipitates were disordered by heavy ion irradiation after 0.06 displacement per atom(dpa).The presence of 2×10-4 atoms helium delayed the disordering of Ni3(Al,Ti)precipitates to 0.68 dpa.With 4×10-4 atoms helium,the precipitates required doses of>2.7 dpa to become disordered.In addition,the precipitation of M23C6 particles were observed at 600℃irradiation to 5.4 dpa with 4×10-4 atoms helium pre-injected.
