The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial press...The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial pressure of 1Pa. and an oxygenpartial pressure of 10^(-19)Pa, both these alloys exhibited three distinct stages in theweight gain-time curve when tested at 700℃. In the initial stage, selective sulfidationof Cr suppressed the formation of the other metal sulfides, resulting in lower weightgains. In the transient stage, breakdown and cracking of Cr sulfides and insufficientconcentration of Cr at the outer zone led to the rapid formation of Ni sulfides anda rapid increase in weight. In the steady-state stage, corrosion was controlled by thediffusion of anions and/or cations, which led to a parabolic rate law.展开更多
The effect of hydrogen on the deformation behavior of three typical kinds of titanium alloys, pure Ti, Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn (Ti-15-3), at high temperature has been investigated by short time creep test. XR...The effect of hydrogen on the deformation behavior of three typical kinds of titanium alloys, pure Ti, Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn (Ti-15-3), at high temperature has been investigated by short time creep test. XRD and TEM techniques are used to examine the changes in their microstructures. The results show that deformation rutes of pure Ti and Ti-6Al-4V alloy can be greatly increased by hydorgen charping due to an increase of β phase volume in their microstructures. β→α transformation is found to occur in unchanged Ti-15-3 alloy during creep process. The addition of 0. 73wt% hydrogen can completely inhibit the deformation-induced transformation and strengthen the metastable β phase in Ti-15-3 alloy, resulting in a dramatic decrease of deformation rate of this alloy at 700° C.展开更多
文摘The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial pressure of 1Pa. and an oxygenpartial pressure of 10^(-19)Pa, both these alloys exhibited three distinct stages in theweight gain-time curve when tested at 700℃. In the initial stage, selective sulfidationof Cr suppressed the formation of the other metal sulfides, resulting in lower weightgains. In the transient stage, breakdown and cracking of Cr sulfides and insufficientconcentration of Cr at the outer zone led to the rapid formation of Ni sulfides anda rapid increase in weight. In the steady-state stage, corrosion was controlled by thediffusion of anions and/or cations, which led to a parabolic rate law.
文摘The effect of hydrogen on the deformation behavior of three typical kinds of titanium alloys, pure Ti, Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn (Ti-15-3), at high temperature has been investigated by short time creep test. XRD and TEM techniques are used to examine the changes in their microstructures. The results show that deformation rutes of pure Ti and Ti-6Al-4V alloy can be greatly increased by hydorgen charping due to an increase of β phase volume in their microstructures. β→α transformation is found to occur in unchanged Ti-15-3 alloy during creep process. The addition of 0. 73wt% hydrogen can completely inhibit the deformation-induced transformation and strengthen the metastable β phase in Ti-15-3 alloy, resulting in a dramatic decrease of deformation rate of this alloy at 700° C.
