F.M.Yang
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X.F.Sun
,
H.R.Guan
,
Z.Q.Hu
金属学报(英文版)
The dynamic strain aging behavior during tensile tests of K40S alloy has been investigated in the temperature range of 25-1100℃ with the strain rate range from 10^-4 to 10^-3s^-1. The results show that four different types of serration, identified as A,B, C and E type serration were observed in the temperature range of 300-500℃. The strain exponents for onset of the serrated flow were calculated as 1.21, 2. 79 and 1.61,and the activation energies as 121, 40 and 67kJ/mol for E, B and C type serration respectively. The main mechanism for dynamic strain aging discussed in light of the strain exponent and the activation energy.
关键词:
dynamic strain aging
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M.H.Li
,
X.F.Sun
,
Z.Y.Zhang
金属学报(英文版)
A bond coat for thermal barrier coating (TBC), NiCrAlY coating, is subjected to vac-uum heat treatment in order to remove internal stress before ceramic top coat is de-posited. The effect of vacuum heat treatment on the oxidation behavior of the sputteredNiCrAlY coating has been investigated. The as-sputtered NiCrAlY coating consists ofγ-Ni and β-NiAl phases. After vacuum heat treatment, the sputtered NiCrAlY coatingmainly consists of γ-Ni3Al, β-NiAl, γ-Ni, and trace of α-Al2O3 phases. The isother-mal oxidation of sputtered NiCrAlY coating with and without vacuum heat treatmenthas been performed at 1000C. It is shown that α-Al2O3 formed during vacuum heattreatment acts as nuclei for the formation of α-Al2O3, and the protective α-Al2O3scale is formed more rapidly on the vacuum heat treated NiCrAlY coating than thatformed on the untreated coating. Also the α-Al2O3 scale has a better adherence to thevacuum heat treated NiCrAlY coating. Therefore the vacuum heat treatment improvesthe oxidation resistance of sputtered NiCrAlY coating.
关键词:
vacuum heat treatment
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