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1

FGMs generated method SHSM

Fraś E., Olejnik E., Janas A., Kolbus A.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 2

123-128

EN

In this study, a new SHSF (Self-Propagating High-Temperature Synthesis in Mould) process of synthesis of the functionally gradient materials (FGMs) was described. The said method enabled generating a thin, sub-surface layer of the MMC type in two alloys, i.e. in cast iron/NbC and Ni3Al/NbC systems. The layer was composed of fine-dispersed niobium carbides present in high volume content. The cast iron/NbC and Ni3Al/NbC materials fabricated by the SHSF process were next subjected to metallographic and structural examinations, combined with testing of mechanical properties.

2

Effect of gas corrosion on the character of phase boundaries in Ni3Al / WC composite

Fraś E., Janas A., Kolbus A., Olejnik E.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 2

87-92

EN

In view of quite specific physico-chemical and performance properties, the composite based on an intermetallic Ni3Al compound reinforced with tungsten carbides (WC) was selected for investigations. The said composite is characterised by very good mechanical and tribological properties within a wide range of temperatures, combined with good corrosion resistance. In fabrication of the Ni3Al/WC composite, a modified variant of the SHS process was applied. It is the SHSB process, i.e. the Self-Propagating High-Temperature Synthesis in Bath. The said method enables obtaining pure products of reaction, unoxidised and free from the precipitates of alien phases. The main goal of this study has been determination of the susceptibility of the Ni3Al/WC composite to gas corrosion. To examine the microstructure and chemical composition of both the composite and the scale, the metallographic and structural examinations were made, using optical and scanning microscopy.

3

Cast in situ composites of Ni3Al / MeC type

Fraś E., Janas A., Kolbus A., Olejnik E.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 2

81-86

EN

In this work a new method SHSB (Self- Propagating High-Temperature Synthesis in Bath) has been used to produce of five new composites i.e.Ni3Al / TiC, Ni3Al / WC, Ni3Al / Zr, Ni3Al / NbC and Ni3Al /TaC (in the amount of carbides of 5% volume fraction.) The composites fabricated by the 'in situ' process, with the Ni3Al compound used as a matrix material and the reinforcement composed of Ti, W, Zr, Nb or Ta carbide particles were made. Fabrication of composites was carried out in Balzers vacuum furnace and conducted the process in the atmosphere of argon at a negative gas pressure of 0,5 MPa. After melting down of aluminium and completion of the exothermic reaction between mixing powder of carbon, aluminium, titanium or tungsten, zirconium, niobium and tantalum, boron in the form of Al-B 3% master alloy was introduced to alloy melt. From thus fabricated composites, the specimens were prepared for metallographic examinations, and scanning topographic analysis. It have been shown that the size of TiC and TaC particles was comprised in a range of up to 10 [...]. The NbC and ZrC carbides were characterised by the dimensions of up to 20 [...], while WC carbides were the largest (up to 80 [...].) In all the examined composites, the X-ray microanalysis revealed total absence of reaction products at the matrix reinforcing particle interface. The SHSB process eliminated the fundamental problem - reactivity of the matrix-particle system, observed in the ex situ methods .

4

SHSB processing and properties of Al/TiC "in-situ" composites

Fraś E., Wierzbiński S., Janas A., Lopez H. F.

Archives of Metallurgy

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2001

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Vol. 46, iss. 4

407-423

EN

A low temperature variant of the self-propagating high temperature synthesis (SHSB. Where the B stands for bath was described and applied to processing "in-situ" AI-TiC composites. It was established that during the SHSB, the undesirable Al4C3 compound, which tends to react with the environment, accompanies the appearance of the TiC one. The Al carbides arc responsible for the degradation of the composite properties by increasing its volume to a large extent. In order to reduce the amounts of the Al4C3 a method has been proposed. The results of structure analysis, as well as strength and abrasion properties have been reported.

PL

W pracy opisano nowy wariant procesu syntezy kompozytów Al/TiC za pomocą samorozprzestrzeniającej się wysokotemperaturowej reakcji egzotermicznej (SHS). Powyższy wariant otrzymywania kompozytów zrealizowano z wykorzystaniem kąpieli aluminiowej i nazwano jako metodę SHSB, gdzie B oznacza kąpiel. Stwierdzono, że podczas syntezy kompozytów metodą SHSB nie tylko otrzymuje się węglik tytanu umacniający aluminum lecz również węgliki aluminium. Węgliki aluminium są niepożądanym składnikiem struktury kompozytów, gdyż wskutek reakcji z atmosferą, jej produkty powiększają swą objętość co prowadzi do rozsypywania się kompozytów. Opracowano metodę minimalizacji ilości niepożądanego węglika aluminium. W pracy podano również wyniki badań strukturalnych, wytrzymałościowych oraz zużycia abrazyjnego otrzymanych kompozytów.