On the strengthening and the strength reducing mechanisms at aluminium matrix composites reinforced with nano-sized TiCN particulates

ABSTRACT

The influence of the volume fraction of nano-sized TiCN reinforcement additive on the mechanical properties and the microstructure of Al-based composite was studied. It was found that the addition of nano-sized TiCN particulates into the Al-matrix leads to a substantial improvement of the mechanical properties of the composite, TiCN-Al. However, the obtained results showed that the strengthening effect depends on the volume fraction of the additive; It was found, that beyond a certain volume fraction of the additive, instead of improving, the mechanical properties of the composite deteriorate. Based on these results a conclusion was drawn that at least two mechanisms, acting concurrently, are operative in the composite, one toward improving the mechanical properties, while the other toward their deterioration. A hypothesis, that the mechanical properties deteriorate due to the development of cracks in the composite’ matrix proved to be correct. Based on the hypothesis a dependence, coupling together the composite's yield strength with the volume fraction of the reinforcement, was proposed and tested. It is shown, that the worked out dependence fits well the obtained experimental data. The effect of the reinforcement agglomeration on the yield strength of the composite is explained and discussed.

KEYWORDS:

• Metal-matrix composites
• nano-sized reinforcement
• strengthening mechanisms
• mechanical properties
• powder metallurgy

Acknowledgments

The authors are indebted to Prof. G. Zlateva (ret.) [53] for the valuable discussions on the TEM micrographs and Mrs. Daniela Shuleva (Space Research and Technology Institute - BAS) for her help in the preparation of the green powder.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

There is no data set(s) associated with this paper.

Additional information

Funding

This work was supported by the Bulgarian National Foundation of Science and Research under Grant, BNSF DN 07/16.