Synthesis of Al-containing MmNi_5 by mechanical alloying: Milling stages, structure parameters and thermal annealing

摘要

In this work, intermetallics of MmNi_(5-x)Al_X composition (Mm = mischmetal = La_(0.25) Ce_(0.52)Nd_(0.17)Pr_(0.06)) where x stands for 0.5 and 1 were synthesized by low energy reactive alloying. Minor structures present on the sample were identified. Structural parameters were calculated. Four stages of milling were characterized as a function of the integrated milling time (t_(im)). The stages were characterized as Initial, Intermediate, Final and Completion. Initial stage ranges from 0 to 20 In. Intermediate and Finai range from 20 to 50 h and from 50 to 120 h, respectively. Completion stage occurs at t_(im) > 120 h. From these results, an optimum milling time was estimated. Energy consumption experiments at laboratory scale were done to optimize annealing parameters and to compare this low energy mechanical alloying-low temperature annealing method with high temperature traditional ones. The optimization was correlated to the structural parameters obtained on the structure. From these results, an improvement on the milling time-annealing process was proposed.