Publication detail

ON THE RELATION BETWEEN DENDRITE MICROHETEROGENEITY INDEX AND EFFECTIVE PARTITION COEFFICIENT OF ELEMENTS IN CREEP-RESISTING Ni-ALLOY BLADES

DOBROVSKÁ, V. DOBROVSKÁ, J. PODRÁBSKÝ, T. STRÁNSKÝ, K.

English title

ON THE RELATION BETWEEN DENDRITE MICROHETEROGENEITY INDEX AND EFFECTIVE PARTITION COEFFICIENT OF ELEMENTS IN CREEP-RESISTING Ni-ALLOY BLADES

Type

journal article - other

Language

en

Original abstract

The chemical microheterogeneity of elements in two cast blades of the first stage of a gas turbine was measured. The first blade was measured in as-cast state, the second one after operation. By means of an original method, the microheterogeneity indíces IH and the effective partition coefficients kef were established. Using a metallographic method, the interdendritic distances, 2L = 32,8 mikro m, of the creep-resisting nickel-alloy blades were measured. By means of the Brody-Flemings (BF) heterogeneity model and with the help of mathematical and statistical methods, a relation between the parameters IH and kef and parameter a = D /L2 of the BF model has been derived. Then the numerical values of parameter alfa from measured heterogeneity data (IH and kef) were calculated and a comparíson was made with literature data. By means of numerical values of parameter alfa it was possible: – to evaluate the relations among diffusion coefftcients D of element of nickel-based alloy (these elements can segregate eitlier in the liquid or in the solid state); – to appreciate the local solidification time 9~, – and to compare the parameters of as-cast and operated blades.

English abstract

The chemical microheterogeneity of elements in two cast blades of the first stage of a gas turbine was measured. The first blade was measured in as-cast state, the second one after operation. By means of an original method, the microheterogeneity indíces IH and the effective partition coefficients kef were established. Using a metallographic method, the interdendritic distances, 2L = 32,8 mikro m, of the creep-resisting nickel-alloy blades were measured. By means of the Brody-Flemings (BF) heterogeneity model and with the help of mathematical and statistical methods, a relation between the parameters IH and kef and parameter a = D /L2 of the BF model has been derived. Then the numerical values of parameter alfa from measured heterogeneity data (IH and kef) were calculated and a comparíson was made with literature data. By means of numerical values of parameter alfa it was possible: – to evaluate the relations among diffusion coefftcients D of element of nickel-based alloy (these elements can segregate eitlier in the liquid or in the solid state); – to appreciate the local solidification time 9~, – and to compare the parameters of as-cast and operated blades.

Keywords in English

microheterogeneity, partition coefficient, Ni-based alloy

RIV year

2001

Released

01.04.2001

ISSN

1335-1532

Volume

7

Number

1/2001

Pages count

5

BIBTEX


@article{BUT40296,
  author="Věra {Dobrovská} and Jana {Dobrovská} and Tomáš {Podrábský} and Karel {Stránský},
  title="ON THE RELATION BETWEEN DENDRITE MICROHETEROGENEITY INDEX AND EFFECTIVE PARTITION COEFFICIENT OF ELEMENTS IN CREEP-RESISTING Ni-ALLOY BLADES",
  year="2001",
  volume="7",
  number="1/2001",
  month="April",
  issn="1335-1532"
}