Mg-RE(rear earth) alloys with long period stacking(LPSO) structures have great potential in biomedical applications. The present work focused on the microstructure and corrosion behaviors of Mg 98.5 Y1 Zn0.5 alloys wi...Mg-RE(rear earth) alloys with long period stacking(LPSO) structures have great potential in biomedical applications. The present work focused on the microstructure and corrosion behaviors of Mg 98.5 Y1 Zn0.5 alloys with 18 R LPSO structure after equal channel angular pressing(ECAP). The results showed that the ECAP process changed the grain size and the distribution of LPSO particles thus controlled the total corrosion rates of Mg 98.5 Y1 Zn0.5 alloys. During the ECAP process from 0 p to 12 p, the grain size reduced from 160–180 μm(as-cast) to 6–8 μm(12 p). The LPSO structures became kinked(4 p), then started to be broken into smaller pieces(8 p), and at last comminuted to fine particles and redistributed uniformly inside the matrix(12 p). The improvement in the corrosion resistance for ECAP samples was obtained from 0 p to 8 p, with the corrosion rate reduced from 3.24 mm/year(0 p) to 2.35 mm/year(8 p) in simulated body fluid, and the 12 p ECAP alloy exhibited the highest corrosion rate of 4.54 mm/year.展开更多
The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperat...The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperature range of 1323-1473 Kand strain rate range of 0.001-0.5s^（-1）.The calculated activation energy in the above variational ranges of temperature and strain rate possesses a low activation energy value of approximately 365.6kJ/mol based on the constitutive relationship models developed with the Arrhenius-type constitutive model respectively considering the strain rate and deformation temperature.The hot working flow behavior during the deformation process was analyzed combined with the microstructural evolution.Meanwhile,the processing maps during the deformation process were established based on the dynamic material model and Prasad instability criterion under different deformation conditions.Finally,the optimal hot processing window of this alloy corresponding to the wide temperature range of 1353-1453 Kand the low strain rate of 0.001-0.1s^（-1） was obtained.展开更多
Based on the Internet technology and artificial int el ligence (AI) technology, this paper presents a dispersed press process knowledge bases based multi-reasoning press process decision system (DKB-MRPPD). The di spe...Based on the Internet technology and artificial int el ligence (AI) technology, this paper presents a dispersed press process knowledge bases based multi-reasoning press process decision system (DKB-MRPPD). The di spersed press process knowledge bases have been organized into case bases and ru le bases, which may be located at different enterprises, and employed to plan pr ess process by a multi-reasoning engine made up of the ART1, case reasoning and rule-based reasoning net. The architecture model of DKB-MRPPD has been put fo rward. The idea and some key technologies for implementing the system have been also discussed in this paper. For easily access the distributed knowledge bases, a Federated knowledge bases System (FKBS) implemented by means of JDBC and CORB A is put forward.展开更多
Addition of Al-5Ti-1B alloy to molten aluminum alloys can refine α-Al grains effectively and thereby improve their strength and toughness. TiAl;and TiB;in Al-5Ti-1B alloy are the main secondary-phase particles for re...Addition of Al-5Ti-1B alloy to molten aluminum alloys can refine α-Al grains effectively and thereby improve their strength and toughness. TiAl;and TiB;in Al-5Ti-1B alloy are the main secondary-phase particles for refinement, while the understanding on the effect of their sizes on α-Al grain refinement continues to be fragmented. Therefore, Al-5Ti-1B alloys with various sizes and morphologies of the secondary-phase particles were prepared by equal channel angular pressing（ECAP）. Evolution of the secondary-phase particles during ECAP process and their impact on α-Al grain refinement were studied by X-ray diffraction and scanning electron microscope（SEM）. Results show that during the ECAP process, micro-cracks firstly appeared inside TiAl;particles and then gradually expanded, which resulted in continuous refinement of TiAl;particles. In addition, micro-distribution uniformity of TiB;particles was improved due to the impingement of TiAl;particles to TiB;clusters during deformation. Excessively large sizes of TiAl;particles would reduce the number of effective heterogeneous nucleus and thus resulted in poor grain refinement effectiveness. Moreover, excessively small TiAl;particles would reduce inhibitory factors for grain growth Q and weaken grain refinement effectiveness. Therefore, an optimal size range of 18-22 μm for TiAl;particles was suggested.展开更多
基金the National Natural Science Foundation of China(Nos.51774109,51979099 and 51901068)the Fundamental Research Funds for the Central Universities(No.2018B690X14)+3 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20191303)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX18_0570)the Key Research and Development Project of Jiangsu Province of China(No.BE2017148)the Public Service Platform Program of Suqian City of China(No.M201614)。
文摘Mg-RE(rear earth) alloys with long period stacking(LPSO) structures have great potential in biomedical applications. The present work focused on the microstructure and corrosion behaviors of Mg 98.5 Y1 Zn0.5 alloys with 18 R LPSO structure after equal channel angular pressing(ECAP). The results showed that the ECAP process changed the grain size and the distribution of LPSO particles thus controlled the total corrosion rates of Mg 98.5 Y1 Zn0.5 alloys. During the ECAP process from 0 p to 12 p, the grain size reduced from 160–180 μm(as-cast) to 6–8 μm(12 p). The LPSO structures became kinked(4 p), then started to be broken into smaller pieces(8 p), and at last comminuted to fine particles and redistributed uniformly inside the matrix(12 p). The improvement in the corrosion resistance for ECAP samples was obtained from 0 p to 8 p, with the corrosion rate reduced from 3.24 mm/year(0 p) to 2.35 mm/year(8 p) in simulated body fluid, and the 12 p ECAP alloy exhibited the highest corrosion rate of 4.54 mm/year.
基金the financial supports from the National Natural Science Foundation of China(Grant Nos.51301157 and 51434007)the National High Technology Research and Development Program of China 863 Program(Grant No.2013AA031103)
文摘The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperature range of 1323-1473 Kand strain rate range of 0.001-0.5s^（-1）.The calculated activation energy in the above variational ranges of temperature and strain rate possesses a low activation energy value of approximately 365.6kJ/mol based on the constitutive relationship models developed with the Arrhenius-type constitutive model respectively considering the strain rate and deformation temperature.The hot working flow behavior during the deformation process was analyzed combined with the microstructural evolution.Meanwhile,the processing maps during the deformation process were established based on the dynamic material model and Prasad instability criterion under different deformation conditions.Finally,the optimal hot processing window of this alloy corresponding to the wide temperature range of 1353-1453 Kand the low strain rate of 0.001-0.1s^（-1） was obtained.
文摘Based on the Internet technology and artificial int el ligence (AI) technology, this paper presents a dispersed press process knowledge bases based multi-reasoning press process decision system (DKB-MRPPD). The di spersed press process knowledge bases have been organized into case bases and ru le bases, which may be located at different enterprises, and employed to plan pr ess process by a multi-reasoning engine made up of the ART1, case reasoning and rule-based reasoning net. The architecture model of DKB-MRPPD has been put fo rward. The idea and some key technologies for implementing the system have been also discussed in this paper. For easily access the distributed knowledge bases, a Federated knowledge bases System (FKBS) implemented by means of JDBC and CORB A is put forward.
基金financial support provided by the National Natural Science Foundation of China(Nos.51674077 and 51474063)
文摘Addition of Al-5Ti-1B alloy to molten aluminum alloys can refine α-Al grains effectively and thereby improve their strength and toughness. TiAl;and TiB;in Al-5Ti-1B alloy are the main secondary-phase particles for refinement, while the understanding on the effect of their sizes on α-Al grain refinement continues to be fragmented. Therefore, Al-5Ti-1B alloys with various sizes and morphologies of the secondary-phase particles were prepared by equal channel angular pressing（ECAP）. Evolution of the secondary-phase particles during ECAP process and their impact on α-Al grain refinement were studied by X-ray diffraction and scanning electron microscope（SEM）. Results show that during the ECAP process, micro-cracks firstly appeared inside TiAl;particles and then gradually expanded, which resulted in continuous refinement of TiAl;particles. In addition, micro-distribution uniformity of TiB;particles was improved due to the impingement of TiAl;particles to TiB;clusters during deformation. Excessively large sizes of TiAl;particles would reduce the number of effective heterogeneous nucleus and thus resulted in poor grain refinement effectiveness. Moreover, excessively small TiAl;particles would reduce inhibitory factors for grain growth Q and weaken grain refinement effectiveness. Therefore, an optimal size range of 18-22 μm for TiAl;particles was suggested.
