Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the p...Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of γ-phase U–Mo alloys using molecular dynamics(MD) simulations. In the slip model, the generalized stacking fault energy(GSFE) and the modified Peierls–Nabarro(P–N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy(GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}<111>slip system is preferentially activated, while in the {112}<111> system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid γ → α′′ transitions, thereby maintaining a higher proportion of γ-phase U–Mo alloys for practical applications.展开更多
Introduction of hard particles is considered an effective approach to improve alloy wear resistances.However,the wear resistances of Mg alloys could be deteriorated by increasing the hard particle content in many rese...Introduction of hard particles is considered an effective approach to improve alloy wear resistances.However,the wear resistances of Mg alloys could be deteriorated by increasing the hard particle content in many researches.To reveal the underlying negative effect of precipitate on the wear resistance,the wear behaviors of three AZ-Mg alloys(precipitate contents:AZ31:2.1%,AZ61:3.8%,AZ91:5.0%)at the axial loads of 3 and 15 N were investigated.The results indicated that although wear volume of the AZ-Mg alloys decreased with the increasing Mg_(17)Al_(12)content at 3 N(0.30→0.24→0.20μm^(3))and 15 N(1.04→0.88→0.85μm^(3)),the relative wear resistances of AZ61 and AZ91 to AZ31 decreased with increasing load(AZ61:1.25→1.17,AZ91:1.50→1.22)and the reduction was proportional to the precipitates content(AZ61:7%,AZ91:28%).That is because the wear volume of AZ-Mg was mainly attributed to micro-cutting,which was negatively correlated with the precipitate content and tribolayer hardness.However,the wear hardening ability of AZ-Mg alloys was weakened by precipitate for its inhibition on the formation of mechanical twins that the precursors for the tribolayer.Moreover,the inhibition of the precipitate on tribolayer could be amplified by the load,resulting in an increase in tribolayer hardness at 3 N(AZ31:0.94,AZ61:1.03,AZ91:1.10 GPa)but a decrease at 15 N(AZ31:1.77,AZ61:1.73,AZ91:1.62 GPa).Therefore,the formation of twin was inhibited by precipitates,which is detrimental to the wear resistance of Mg alloys.That means the wear resistance could be enhanced by promoting twin formation,which provides a new concept for the design of wear-resistant Mg alloys.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 52271105)。
文摘Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of γ-phase U–Mo alloys using molecular dynamics(MD) simulations. In the slip model, the generalized stacking fault energy(GSFE) and the modified Peierls–Nabarro(P–N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy(GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}<111>slip system is preferentially activated, while in the {112}<111> system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid γ → α′′ transitions, thereby maintaining a higher proportion of γ-phase U–Mo alloys for practical applications.
基金supported by the National Natural Science Foundation of China(No.52101084)the General Program of National Natural Science Foundation of China(NO.52075544)+2 种基金Key Research and Development Plan of Guang Dong(NO.2023B0909020002)Guangdong Basic and Applied Basic Research Foundation(NO.2023A1515011579and 2024A1515030004)the Open Fund Projects of Key Lab of Industrial Fluid Energy Conservation and Pollution Control(Ministry of Education),Qingdao University of Technology(NO.CK20240045).
文摘Introduction of hard particles is considered an effective approach to improve alloy wear resistances.However,the wear resistances of Mg alloys could be deteriorated by increasing the hard particle content in many researches.To reveal the underlying negative effect of precipitate on the wear resistance,the wear behaviors of three AZ-Mg alloys(precipitate contents:AZ31:2.1%,AZ61:3.8%,AZ91:5.0%)at the axial loads of 3 and 15 N were investigated.The results indicated that although wear volume of the AZ-Mg alloys decreased with the increasing Mg_(17)Al_(12)content at 3 N(0.30→0.24→0.20μm^(3))and 15 N(1.04→0.88→0.85μm^(3)),the relative wear resistances of AZ61 and AZ91 to AZ31 decreased with increasing load(AZ61:1.25→1.17,AZ91:1.50→1.22)and the reduction was proportional to the precipitates content(AZ61:7%,AZ91:28%).That is because the wear volume of AZ-Mg was mainly attributed to micro-cutting,which was negatively correlated with the precipitate content and tribolayer hardness.However,the wear hardening ability of AZ-Mg alloys was weakened by precipitate for its inhibition on the formation of mechanical twins that the precursors for the tribolayer.Moreover,the inhibition of the precipitate on tribolayer could be amplified by the load,resulting in an increase in tribolayer hardness at 3 N(AZ31:0.94,AZ61:1.03,AZ91:1.10 GPa)but a decrease at 15 N(AZ31:1.77,AZ61:1.73,AZ91:1.62 GPa).Therefore,the formation of twin was inhibited by precipitates,which is detrimental to the wear resistance of Mg alloys.That means the wear resistance could be enhanced by promoting twin formation,which provides a new concept for the design of wear-resistant Mg alloys.
