Melting behavior of nanocrystalline aluminum powders

• Published in: Nanostructured materials Vol. 2; no. 4; pp. 407 - 413
• Main Authors: Eckert, J., Holzer, J.C., Ahn, C.C., Fu, Z., Johnson, W.L.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Science 1993; Elsevier
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Materials synthesis; materials processing; Metals. Metallurgy; Physics; Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation; Grain size; Powders; Fusion heat; Controlled atmospheres; Aluminium; Powder grinding; XRD; Experimental study; Microstructure; Melting points; Attrition; Nanocrystal
• ISSN: 0965-9773; 1872-9150
• DOI: 10.1016/0965-9773(93)90183-C

Nanocrystalline aluminum powders have been synthesized by mechanical attrition under different atmospheres and by gas condensation. The crystal refinement and the development of the microstructure are investigated by x-ray diffraction, differential scanning calorimetry, transmission electron microscopy, and electron energy loss spectrometry. Both preparation techniques lead to powders with comparable grain sizes. With decreasing grain size we find a drastic reduction of the melting point, ΔT m, in comparison to the bulk value. Subsequent remelting does not recover the bulk melting point. The results are discussed in terms of the microstructure of the nanocrystalline powders, the contribution of the stored enthalphy of cold work, and the nucleation of disorder/melting at grain boundaries/particle interfaces.