F.S.Liu
,
J.L.Xu
,
C.G.Zhou
,
S.K.Gong
,
H.B.Xu
金属学报(英文版)
The halide-activated pack cementation method is utilized to codeposit aluminum and silicon on Mo substrate. Emphasis is placed on the microstructure and elevated-temperature oxidation resistance of coatings. The results show that hexagonal Mo (Si, Al)2 as a main phase and a little amount of the lower disilicide Mo3Si3 was formed on Mo substrate through the halide-activated pack cementation method. The resultant Si-Al coating on Mo substrate exhibits excellent cyclic oxidation resistance. The excellent cyclic oxidation resistance of the coatings is attributed to the formation of alumina on the coatings during the oxidation.
关键词:
Mo(Si
,
null
,
null
,
null
Y.Q.Ma
,
C.B.Jiang
,
H.B.Xu
金属学报(英文版)
Cu-Al-Co and Cu-Al-Zr alloys were explored with Co or Zr additions in Cu-Al alloys for high temperature shape memory alloys. Samples were quenched after homogenized at 850℃ for 48h. It was found that both Cu-Al-Co and Cu-Al-Zr show AlCus martensitic phase at room temperature and exhibit martensitic transformation temperatureshigher than 200℃, showing the potentials for developing as high temperature shape memory alloys. Thermal cycles were performed by DSC instrument on both Cu-Al-Co and Cu-Al-Zr alloys. The results show that Cu-Al-Co loses its martensitic transformation after five thermal cycles, and Cu-Al-Zr exhibits no martensitic transformation in the second thermal cycle.
关键词:
shape memory alloy
,
null
X.F.Bi
,
S.K.Gong
,
H.B.Xu
金属学报(英文版)
Fe-Cu thin films of 0.2μm in thickness with different Cu contents were prepared byusing r.f. magnetron sputtering onto glass substrate. The effect of sputtering param-eters, including Ar gas pressure and input rf power, on the structure and magneticproperties was investigated. It was found that when the power is lower than 70W,the structure of the films remained single bcc-Fe phase with Cu solubility of up to50at.%. TEM observations for the bcc-Fe phase showed that the grain size was inthe nanometer range of less than 20nm. The coercivity of Fe-Cu films was largelyaffected by not only Ar gas pressure but also rf power, and reached about 2.5Oe in thepressure of 0.67-6.67Pa and in the power of less than 100W. In addition, saturationmagnetization, with Cu content less than 60at.%, was about proportional to the con-tent of bcc-Fe. When Cu content was at 60at.%, however, saturation magnetizationwas much smaller than its calculation value.
关键词:
Fe-Cu thin film
,
null
,
null
,
null
J.S.Yu
,
C.G.Zhou
,
H.B.Xu
金属学报(英文版)
The oxidations of low pressure plasma sprayed (LPPS) NiCrAlY coating on nickelbase superalloy were studied at 1050C in flows of O2, and mixture of O2 and 5%H2 Ounder atmospheric pressure. Oxide formed on the surface of LPPS NiCrAlY coatingafter oxidation at 1050℃ in pure O2 consisted of NiCr2 O4, whereas oxide formed onthe surface of LPPS NiCrAlY coating after oxidation at 1000℃ in a mixture of O2 and5%H2 O is mainly composed of NiO. The effect of water vapor on the characteristicsof the oxide scale is attributed to the increase in Ni cation transport.
关键词:
oxidation
,
null
,
null
D.B.Zhang
,
S.K.Gong
,
H.B.Xu
金属学报(英文版)
Conventional two-layered structure thermal barrier coatings (TBCs) were preparedonto γ'-Ni3Al based alloy IC-6 by electron beam physical vapor deposition (EB-PVD).Isothermal oxidation and thermal cycling tests were carried out to investigate theeffect of Mo content at the interface between bond coat and ceramic top coat causedby diffusion. It has been found that the alloy coated with TBCs presented the lowestoxidation weight gain value for the reason that the ceramic top coat in TBC systemcan effectively stop Mo oxides evaporating. The life time of TBCs has close relationwith Mo content at the interface between the bond coat and top coat. Spallation ofceramic top coat occurred during thermal cyclic testing when Mo atoms accumulatedat the interface up to certain amount to decline the combination between the bond coatand top coat.
关键词:
EB-PVD
,
null
,
null
,
null
