Effect of the Preparation Methods of Me+Al Powder Blends on the Compaction Behavior, Structure, Phase Transformations, and Properties of the Compacted Aluminides of Transition Metals
The effect of the methods for preparing powder blend by conventional milling (Me+Al particles), attriting (Me/Al/ Me/Al composite particles), and plating of Me by Al (Me/Al composite particles) on the structure, internal stress level, and compactability of the powder blends as well as the structure and phase composition of the MeAl compacts was investigated. The Me+Al→MeAl exothermic reaction of these powders occurs at T≥650°C. The reaction sintering (RS) or hightemperature self-propagation synthesis (HTSPS) occurs through the formation of Al melt (liquidphase reaction) and lower-melting MeAl3, Me2Al3, Me3Al aluminides. An increase in the level of internal stresses (IS) upon attritting activates RS at lower temperatures and decreases the value of high-temperature exoeffect. This suppresses the HTSPS development. A large high-temperature exoeffect ensures the intensity and completeness of the reaction interaction, and the application of pressure upon RS or HTSPS provides a high, near-theoretical density of the compacted material.
Duk Yong Yoon, Suk-Joong L. Kang, Kwang Yong Eun and Yong-Seog Kim
K.B. Povarova et al., "Effect of the Preparation Methods of Me+Al Powder Blends on the Compaction Behavior, Structure, Phase Transformations, and Properties of the Compacted Aluminides of Transition Metals", Materials Science Forum, Vols. 534-536, pp. 513-516, 2007