| 1. |
- Hillert, Mats, et al.
(författare)
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Escape of carbon from ferrite plates in austenite
- 1993
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Ingår i: ACTA METALL MATER. - 0956-7151. ; 41:7, s. 1951-1957
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Tidskriftsartikel (refereegranskat)abstract
- A newly developed computer program for the simulation of diffusional transformations has been applied to study the escape of carbon from a plate of ferrite assuming that the plate initially formed by a partitionless reaction from an Fe-C austenite. Thereafter the ferrite austenite interface was assumed to be immobile and local equilibrium was assumed for carbon but not for iron. The process first follows a parabolic rate law and is there controlled by the rate of diffusion in ferrite. Later stages are not parabolic and are controlled by the diffusivity in austenite. Its concentration dependence was taken into account. It was found that the rate could be estimated analytically using the maximum value rather than the average value.
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| 2. |
- Li, W.B., et al.
(författare)
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Model for nano-indentation creep
- 1993
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Ingår i: Acta Metallurgica et Materialia. - 0956-7151. ; 41:10, s. 3065-3069
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Tidskriftsartikel (refereegranskat)abstract
- A new model is developed to describe that stage of nano-intentation creep prior to `pop-in', i.e. when the indentation load induces purely elastic stresses within the sample. Expressions for the stress fields due to a conical indenter are derived and the resulting chemical potential and diffusion fluxes established. The considerations lead to a creep rate equation which is found to fit well with existing experimental data on tungsten. The model is hence used to predict nano-indentation creep rates at various temperatures. It is found, for example, that at a temperature as low as 100 °C, the indentation creep rate of tungsten can be considerable
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| 3. |
- Xie, Z.L., et al.
(författare)
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Isothermal martensitic transformation under hydrostatic pressure in an Fe-Ni-C alloy at low temperatures
- 1993
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Ingår i: Acta Metallurgica Et Materialia. - Oxford : Elsevier Science Ltd. - 0956-7151. ; 41:8, s. 2283-2290
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Tidskriftsartikel (refereegranskat)abstract
- The isothermal martensitic tranformation under applied hydrostatic pressure has been investigated with an Fe-21.5Ni-0.95C alloy single crystal by electrical resistivity, magnetic susceptibility, X-ray diffraction and optical microscopy. The martensitic transformation starting temperature, M(s), is lowered by applied hydrostatic pressure. The isothermal martensitic transformation occurs first as a burst under a critical pressure and it is continued by further transformation with decreasing hydrostatic pressure The critical pressure under which the isothermal martensitic transformation starts changes curvilinearly with decreasing temperature. The morphology of the isothermal martensite formed under hydrostatic pressure is similar to that of athermal martensite. The temperature dependence of the critical pressure under which martensitic transformation starts has been calculated based on the homogeneous nucleation model and the heterogeneous nucleation model.
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