Based on the previous work on the mechanical alloying of Ni-Al-Ti compounds. the mechanically alloyed Ni-Al-Ti compounds was characterized. The results show that with the increase of Ti content. the microhardness of t...Based on the previous work on the mechanical alloying of Ni-Al-Ti compounds. the mechanically alloyed Ni-Al-Ti compounds was characterized. The results show that with the increase of Ti content. the microhardness of the final products decrease apparently. The thermal behavior of the resultant Ni-Al-Ti compounds shows significant difference, the as-milled powders with different Ti content transform into different products after healing.So the microstructure of the milled alloys could be determined through adequate control of composition and heat treatments.展开更多
Phase equilibria including γ,γ′,η,β and H in Ni Al Ti system were investigated by diffusion couple method and calculated with thermodynamic model.The experimental phase equilibria generally agree with ones ...Phase equilibria including γ,γ′,η,β and H in Ni Al Ti system were investigated by diffusion couple method and calculated with thermodynamic model.The experimental phase equilibria generally agree with ones reported till now.Regular solution and sublattice models were used in order to calculate these phase equilibria.The calculated results show agreement with experimental data.展开更多
In this study, Cf/Al composites and TiAl alloys were joined by a new method named laser-ignited selfpropagating synthesis（SHS）. Mixed powders of 63.0Ni-31.9Al-5.1Ti（wt%） were used as joining interlayer.Perfect joi...In this study, Cf/Al composites and TiAl alloys were joined by a new method named laser-ignited selfpropagating synthesis（SHS）. Mixed powders of 63.0Ni-31.9Al-5.1Ti（wt%） were used as joining interlayer.Perfect joint was got. The microstructure evolution and formation mechanism of the SHS joint were investigated by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS） and X-ray diffraction（XRD）. Results show that localized melting occurs on both sides. One γ-Ni（0.35）Al（0.30）Ti（0.35） and two Ni-Al reaction layers form,respectively, in the TiAl/interlayer and Cf/Al/interlayer interfaces. The combustion of Ni-Al-Ti interlayer begins with the sharp reaction of Ni and Al. The interlayer product is a eutectic organization of NiAl and Al-rich γ.展开更多
In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack...In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.展开更多
文摘Based on the previous work on the mechanical alloying of Ni-Al-Ti compounds. the mechanically alloyed Ni-Al-Ti compounds was characterized. The results show that with the increase of Ti content. the microhardness of the final products decrease apparently. The thermal behavior of the resultant Ni-Al-Ti compounds shows significant difference, the as-milled powders with different Ti content transform into different products after healing.So the microstructure of the milled alloys could be determined through adequate control of composition and heat treatments.
文摘Phase equilibria including γ,γ′,η,β and H in Ni Al Ti system were investigated by diffusion couple method and calculated with thermodynamic model.The experimental phase equilibria generally agree with ones reported till now.Regular solution and sublattice models were used in order to calculate these phase equilibria.The calculated results show agreement with experimental data.
基金financially supported by the National Natural Science Foundation of China(No.51075101)
文摘In this study, Cf/Al composites and TiAl alloys were joined by a new method named laser-ignited selfpropagating synthesis（SHS）. Mixed powders of 63.0Ni-31.9Al-5.1Ti（wt%） were used as joining interlayer.Perfect joint was got. The microstructure evolution and formation mechanism of the SHS joint were investigated by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS） and X-ray diffraction（XRD）. Results show that localized melting occurs on both sides. One γ-Ni（0.35）Al（0.30）Ti（0.35） and two Ni-Al reaction layers form,respectively, in the TiAl/interlayer and Cf/Al/interlayer interfaces. The combustion of Ni-Al-Ti interlayer begins with the sharp reaction of Ni and Al. The interlayer product is a eutectic organization of NiAl and Al-rich γ.
基金Projects(YKJ201203,CKJB201205)supported by the Nanjing Institute of Technology,China
文摘In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.
