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1

The effect of graphite precipitates in Ni3Al/C composite on tribological properties

Janas A., Kmita A.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

315--318

EN

The study shows the results of investigations of the tribological properties of cast Ni3Al/C composite and compares them with the properties of pure intermetallic phases of the Ni3Al type. An inspiration to these studies was a surprising similarity observed between the microstructure of iron-carbon alloys, and specifically of different cast iron grades, and the microstructure of, absolutely different in terms of the chemical composition, nickel-aluminium alloy. Because of carbon present in the alloy, an attempt was made to determine what effect the presence of graphite (acting as a lubricant) might have on the abrasive wear behaviour of alloy during lubricated friction test. Tests were made on a Miller apparatus, used for active testing of the abrasive wear resistance. The specimen loss of mass was determined in function of time.

2

Synthesis and evaluation of the structure of Ni3Al/C alloy

Kmita A., Janas A., Hutera B.

Metallurgy and Foundry Engineering

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2009

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Vol. 35, no. 2

147-154

EN

The article specifies a method used for the manufacture of a new Ni-Al-C alloy with the description of alloy microstructure. When proper conditions are maintained, the said alloy after solidification forms a natural "in situ" Ni3Al/C composite. Particular attention was paid to the process of synthesis of Ni3Al phase by the technique of cost-effective melting and to the process of the formation of different graphite forms after the solidification in ceramic mould of casting characterised by different wall cross-sections, and hence by different heat transfer rates. Metallographic examinations were carried out by the commonly used techniques and by scanning electron microscopy. The use of the latter enabled the determination of the chemical composition of phases formed during casting process. The aim of the present studies was to evaluate the microstructure of this unique alloy. The phase morphologies were examined and their chemical composition was determined. These fundamental studies should enable the determination of conditions under which the graphite eutectic is formed in Ni-Al alloy and, as a consequence, the synthesis of Ni3Al/C composite.

PL

W prezentowanym artykule przedstawiono metodę otrzymywania nowego stopu Ni-Al-C oraz opisano jego mikrostrukturę. Przy zachowaniu odpowiednich warunków stop ten, po procesie krystalizacji, tworzy naturalny kompozyt ,,in situ" Ni3Al/C. Zwrócono szczególną uwagę na proces syntezy fazy Ni3Al metodą OPW (oszczędnościowego procesu wytopu) i tworzenia się różnych form grafitu po procesie krystalizacji w formie ceramicznej, przy różnych grubościach odlewu, co za tym idzie, przy różnych prędkościach odprowadzenia ciepła. Do badań metaloznawczych wykorzystano tradycyjne metody metalograficzne oraz badania z wykorzystaniem mikroskopu skaningowego. Zastosowanie tego ostatniego umożliwiło określenie składu chemicznego faz, wytworzonych w procesie odlewniczym. Celem podjętych badań było dokonanie oceny mikrostruktury tego nietypowego stopu. Zbadano morfologię występujących faz i określono ich skład chemiczny. Te badania o charakterze podstawowym, pozwolą określić warunki powstawania eutektyki grafitowej w stopie Ni-Al, co w konsekwencji umożliwi syntezę kompozytu Ni3Al/C.

3

Processing and mechanical properties of mechanically alloyed niobum-rich Nb-Al alloys.

Dymek S., Dollar M., Leonard K., Wróbel M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1147-1152

EN

Four Nb-Al alloys containing 15%, 18%, 20% and 25% at. Al were successfully processed by mechanical alloying followed by hot pressing. Analysis of X-ray spectra as well as transmission electron microscopy studies revealed the presence of four phases: niobum solid solution (Nbss), NB3Al, Nb2Al and dispersoids of Al2O3. The grain size was estimated to be = 1 micrometre. The improvement in strength of the mechanically alloyed material was due to the refined grain size and oxide dispersion in the microstructure. The alloys exhibited only limited compressive ductility at room temperature but were ductile at 1000 degrees centigrade. The mechanism for creep deformation in the examined Nb-Al alloys is postulated to be dislocation creep through diffusion controlled climb.

4

Manufacturing of intermetallic materials in Ti-Al and Fe-Al systems by SHS.

Godlewska E., Koziński S., Mania R., Wsołek M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

929-932

EN

The paper presents investigations on manufacturing titanium aluminide, TiAl, and iron aluminide, FeAl, by self-propagating high-temperature synthesis (SHS) combined with hot pressing (HP) or hot forging (HF). TiAl was prepared from equimolar powder mixture of titanium hydride and aluminium. FeAl was obtained directly from metal powders, the Fe/Al atomic ratio being 60:40. The SHS process was carried out in an Ar/H2 gas mixtures, using global ignition technique. Chemical and phase composition as well as morphology, density and porosity were analysed after each processing step. Selected samples were subjected to mechanical testing.

5

Dispersion hardened Al-Me-SiC powders obtained by the mechanical alloying method.

Formanek B., Gierek A., Szopiński K.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1211-1214

EN

The mechanical alloying of Al-Ti-SiC and Al-Ni-SiC composite powders is presented in the article. The process parameters and morphology of powders were determined. The results allow to apply the agglomerated powders for sintering and thermal spraying processes.

6

Composite aluminide - oxide phase powders for thermal spraying processes.

Formanek B., Hetmańczyk M., Szymański K.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1019-1022

EN

Article presents technological conception of composite powders manufacturing by the SHS method in the system of iron and titanium aluminides and aluminium and titanium oxides. High temperature synthesis parameters and the phase composition of powders were determined. The obtained powders are used for forming thermal barrier coatings.