Dan LI
,
Yousong GU
,
Xiangrong CHANG
,
Fushen LI
,
Lijie QIAO
,
Zhongzhuo TIAN
材料科学技术（英文）
200 nm thick Fe-N magnetic thin films were deposited on glass substrates by RF sputtering. The as-deposited films have high saturation magnetization but their coercivity is also higher than what is needed Therefore it is very important to reduce coercivity. The samples were vacuum annealed at 250 °C under 12000 A/m magnetic field. When the N content was in the range of 5~7 at.pct, the thin films consisted of α'+α'' after heat treatment and had excellent soft magnetic properties of 4πM2=2.4 T, Hc<80 A/m. However, the thickness of a recording head was 2 μm, and Hc increased as thickness increased. In order to reduce the Hc, the sputtering power was raised from 200 W to 1000 W to reduce the grain size. 2 μm Fe-N thin films were vacuum annealed under the same condition, when the N content was in the range of 5.9~8.5 at.pct, the thin films kept its excellent magnetic properties of 4πM2=2.2 T, Hc<80 A/m. The properties of the films meet the need of a recording head material used in the dual-element GMR/inductive heads.
关键词:
Fe-N
,
null
,
null
Hong LU
,
Kewei GAO
,
Hui LIU
,
Lijie QIAO
,
Wuyang CHU
材料科学技术（英文）
alpha -Ti foil with a protective layer formed on one side was deflected during corrosion in a methanol solution containing 0.6 mol/L KCl and then a tensile stress was generated at or near the metal passive film interface. The in situ TEM observation showed that corrosion process could facilitate dislocation emission and motion. Adding 10% H2O into the methanol solution decreased the passive film-induced stress from 320 MPa to zero, and the susceptibility to SCC measured in slow strain rate tests decreased correspondingly from 98% to zero.
关键词:
Chuan PAN
,
Zhengbang LI
,
Zhiling TIAN
,
Dongtu LIANG
,
Lijie QIAO
,
Wuyang CHU
材料科学技术（英文）
For 308L and 347L weld metals of austenitc stainless steels (ASS), hydrogen induced cracking (HIC) occurred during dynamically charging under constant load. The threshold stress intensity for HIC, KIH, decreased linearly with the logarithm of the concentration of diffusible hydrogen C0 in the weld metals and the rolled plate of type 304L ASS, i.e., KIH=85.2-10.7ln C0 (308L),KIH=76.1-9.3ln C0(347L), and KIH=91.7-10.1ln C0(304L). The fracture mode for HIC in the three type of ASS changed from ductile to brittle with the decrease in the applied stress intensity KI or/and the increase in C0. The boundary line between ductile and brittle fracture surfaces was KI-54+25exp(-C 0/153)=0.
关键词:
Austenitic stainless steel
,
null
,
null
Jinxu LI
,
Yanbin WANG
,
Lijie QIAO
,
Wuyang CHU
材料科学技术（英文）
Hydrogen-induced cracking (HIC) of two-phase alloy of Ni3Al+NiAl was in situ investigated using a WOL (wedge opening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scanning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was KIH=15.7 MPa·m1/2, and (da/dt)II=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially within the NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of 24.7×10-4%, hydrogen-induced crack initiated and propagated preferentially along the Ni3Al/NiAl interfaces, resulting in interphase fracture.
关键词:
Ni3Al+NiAl
,
null
,
null
,
null
