以氢化钛(TiH2)粉代替钛粉,与氮化铝(AlN)粉体混合,合成高纯的三元氮化物Ti2AlN陶瓷粉体。氢化钛与氮化铝按照摩尔比2∶1的配比,在混料机中混合12 h,然后放入流动氩气气氛保护的管式炉中高温处理。通过对在不同温度以及不同时间下进行...以氢化钛(TiH2)粉代替钛粉,与氮化铝(AlN)粉体混合,合成高纯的三元氮化物Ti2AlN陶瓷粉体。氢化钛与氮化铝按照摩尔比2∶1的配比,在混料机中混合12 h,然后放入流动氩气气氛保护的管式炉中高温处理。通过对在不同温度以及不同时间下进行热处理得到的产物进行物相分析,探究Ti2AlN的形成机理,发现在1400℃下保温2 h得到的Ti2AlN粉体纯度最高,约为96.2%(质量分数)。在同样条件下,以钛粉为钛源合成Ti2AlN粉体的纯度只有80.2%(质量分数)。因为氢化钛粉体价格低于钛粉,并且合成的样品纯度显著提高。所以,以氢化钛粉代替钛粉为钛源,合成Ti2AlN具有显著优势。同时研究了所合成Ti2AlN粉体在不同酸溶液(KF-HCl、NaF-HCl和NH4F-HCl)腐蚀行为。结果发现:将Ti2AlN(~2 g)浸入由2 g KF溶解在40 mL 6 M HCl的KF-HCl混合液中,在50℃下搅拌48 h得到碎片团簇型TiN。但是二维碳化物Ti2N MXene不能通过选择性刻蚀Ti2AlN的方法得到。展开更多
Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃...Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃ for 24 h after being heat treated at 1400 ℃ for 0.5 h. The in-situ composites consist of γ＋α2 lamellar colonies, equiaxed y grains and Ti2AlN reinforcements. Matrix with nearly fully lamellar structure formed after solution and subsequently aging treatment. With the increase of Ti2AlN content, the nearly fully lamellar structure becomes instable for the aged composites. According to TEM study, fine Ti2AlN precipitates are found to distribute at the grain boundaries of lamellar colony. Needle-like Ti3AlN precipitates arrange in line with growing axis parallel to [001] direction of the γ-TiAl matrix and another needle-like Ti3AlN precipitates with lager size distribute at the dislocations. Key words：展开更多
High-purity Ti2AlN ceramic was prepared at 1300 ℃ by hot pressing(HP)of Ti/Al/TiN powders in stoichiometric proportion.The sintered product was characterized using X-ray diffraction(XRD)and MDI Jade 5.0 software(Mate...High-purity Ti2AlN ceramic was prepared at 1300 ℃ by hot pressing(HP)of Ti/Al/TiN powders in stoichiometric proportion.The sintered product was characterized using X-ray diffraction(XRD)and MDI Jade 5.0 software(Materials Data Inc,Liverpool,CA).Scanning electron microscopy(SEM)and electron probe micro-analysis(EPMA)coupled with energy-dispersive spectroscopy(EDS)were utilized to investigate the morphology characteristics.The results show that Ti2AlN phase is well-developed with a close and lamellar structure.The grains are plate-like with the size of 3-5 μm,thickness of 8-10 μm and elongated dimension.The density of Ti2AlN is measured to be 4.22 g/cm3,which reaches 97.9% of its theory value.The distribution of Ti2AlN grains is homogeneous.展开更多
Mn+1AXn(MAX) phases are a family of nanolaminated compounds that possess unique combination of typical ceramic properties and typical metallic properties.As a member of MAX phase,Ti2 AlN bulk materials are attractive ...Mn+1AXn(MAX) phases are a family of nanolaminated compounds that possess unique combination of typical ceramic properties and typical metallic properties.As a member of MAX phase,Ti2 AlN bulk materials are attractive for some high-temperature applications.The synthesis,characteristics and machining performance of hybrid Ti2 AlN bulk materials were focused on in this work.The bulk samples mainly consisting of Ti2 AlN MAX phase with density close to theoretic one were synthesized by a spark plasma sintering method.Scanning electron microscopy results indicate homogenous distribution of Ti2 AlN grains in the samples.Micro-hardness values are almost constant under different loads (6-6.5 GPa).A machining test was carried out to compare the effect of material properties on micro-electrical discharge machining (micro-EDM) performance for Ti2 AlN bulk samples and Ti6242 alloy.The machining performance of the Ti2 AlN sample is better than that of the Ti6242 alloy.The inherent mechanism was discussed by considering their electrical and thermal conductivity.展开更多
The stability of Ti2AlN at high pressure of 5 GPa and different temperatures of 700-1 600 ℃ was investigated using X-ray diffraction （XRD）,scanning electron microscopy （SEM） equipped with an energy dispersive spe...The stability of Ti2AlN at high pressure of 5 GPa and different temperatures of 700-1 600 ℃ was investigated using X-ray diffraction （XRD）,scanning electron microscopy （SEM） equipped with an energy dispersive spectrometer （EDS）.Ti2AlN was found to be stable at temperatures as high as 1 400 ℃under 5 GPa for 20 min,and was proved that it held better structure stability than Ti2AlC under 5 GPa through comparative experiments of Ti2AlN and Ti2AlC （representative compounds of M2AX phases （211 phase））.The reaction process at high pressure had some difference from that at ambient pressure/vacuum,and Ti2AlN directly decomposed to TiN and TiAl at 5 GPa and 1 500 ℃ for 20 min.Moreover,the mechanism of phase segregation was discussed.In addition,the behavior of Ti2AlN contacting with Zr at high pressure and high temperature （HPHT） was also studied.展开更多
文摘以氢化钛(TiH2)粉代替钛粉,与氮化铝(AlN)粉体混合,合成高纯的三元氮化物Ti2AlN陶瓷粉体。氢化钛与氮化铝按照摩尔比2∶1的配比,在混料机中混合12 h,然后放入流动氩气气氛保护的管式炉中高温处理。通过对在不同温度以及不同时间下进行热处理得到的产物进行物相分析,探究Ti2AlN的形成机理,发现在1400℃下保温2 h得到的Ti2AlN粉体纯度最高,约为96.2%(质量分数)。在同样条件下,以钛粉为钛源合成Ti2AlN粉体的纯度只有80.2%(质量分数)。因为氢化钛粉体价格低于钛粉,并且合成的样品纯度显著提高。所以,以氢化钛粉代替钛粉为钛源,合成Ti2AlN具有显著优势。同时研究了所合成Ti2AlN粉体在不同酸溶液(KF-HCl、NaF-HCl和NH4F-HCl)腐蚀行为。结果发现:将Ti2AlN(~2 g)浸入由2 g KF溶解在40 mL 6 M HCl的KF-HCl混合液中,在50℃下搅拌48 h得到碎片团簇型TiN。但是二维碳化物Ti2N MXene不能通过选择性刻蚀Ti2AlN的方法得到。
基金Project(2011CB605502)supported by the National Basic Research Program of ChinaProject(51001086)supported by the National Natural Science Foundation of China
文摘Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃ for 24 h after being heat treated at 1400 ℃ for 0.5 h. The in-situ composites consist of γ＋α2 lamellar colonies, equiaxed y grains and Ti2AlN reinforcements. Matrix with nearly fully lamellar structure formed after solution and subsequently aging treatment. With the increase of Ti2AlN content, the nearly fully lamellar structure becomes instable for the aged composites. According to TEM study, fine Ti2AlN precipitates are found to distribute at the grain boundaries of lamellar colony. Needle-like Ti3AlN precipitates arrange in line with growing axis parallel to [001] direction of the γ-TiAl matrix and another needle-like Ti3AlN precipitates with lager size distribute at the dislocations. Key words：
基金Project(50572080)supported by the National Natural Science Foundation of ChinaProject(SYSJJ2005-04)supported by the Open Foundation of Key Laboratory of Silicate Materials Science and Engineering(Wuhan University of Technology),Ministry of Education
文摘High-purity Ti2AlN ceramic was prepared at 1300 ℃ by hot pressing(HP)of Ti/Al/TiN powders in stoichiometric proportion.The sintered product was characterized using X-ray diffraction(XRD)and MDI Jade 5.0 software(Materials Data Inc,Liverpool,CA).Scanning electron microscopy(SEM)and electron probe micro-analysis(EPMA)coupled with energy-dispersive spectroscopy(EDS)were utilized to investigate the morphology characteristics.The results show that Ti2AlN phase is well-developed with a close and lamellar structure.The grains are plate-like with the size of 3-5 μm,thickness of 8-10 μm and elongated dimension.The density of Ti2AlN is measured to be 4.22 g/cm3,which reaches 97.9% of its theory value.The distribution of Ti2AlN grains is homogeneous.
基金Project supported by a 2-Year Research Grant of Pusan National University,KoreaProject(2010-0008-277)partly supported by NCRC Program funded by the Ministry of Education,Science and Technology
文摘Mn+1AXn(MAX) phases are a family of nanolaminated compounds that possess unique combination of typical ceramic properties and typical metallic properties.As a member of MAX phase,Ti2 AlN bulk materials are attractive for some high-temperature applications.The synthesis,characteristics and machining performance of hybrid Ti2 AlN bulk materials were focused on in this work.The bulk samples mainly consisting of Ti2 AlN MAX phase with density close to theoretic one were synthesized by a spark plasma sintering method.Scanning electron microscopy results indicate homogenous distribution of Ti2 AlN grains in the samples.Micro-hardness values are almost constant under different loads (6-6.5 GPa).A machining test was carried out to compare the effect of material properties on micro-electrical discharge machining (micro-EDM) performance for Ti2 AlN bulk samples and Ti6242 alloy.The machining performance of the Ti2 AlN sample is better than that of the Ti6242 alloy.The inherent mechanism was discussed by considering their electrical and thermal conductivity.
基金Funded by the National Natural Science Foundation of China (Nos.50572067,10772126)
文摘The stability of Ti2AlN at high pressure of 5 GPa and different temperatures of 700-1 600 ℃ was investigated using X-ray diffraction （XRD）,scanning electron microscopy （SEM） equipped with an energy dispersive spectrometer （EDS）.Ti2AlN was found to be stable at temperatures as high as 1 400 ℃under 5 GPa for 20 min,and was proved that it held better structure stability than Ti2AlC under 5 GPa through comparative experiments of Ti2AlN and Ti2AlC （representative compounds of M2AX phases （211 phase））.The reaction process at high pressure had some difference from that at ambient pressure/vacuum,and Ti2AlN directly decomposed to TiN and TiAl at 5 GPa and 1 500 ℃ for 20 min.Moreover,the mechanism of phase segregation was discussed.In addition,the behavior of Ti2AlN contacting with Zr at high pressure and high temperature （HPHT） was also studied.
