Improvement of as-milled properties of mechanically alloyed LaNi 5 and application to hydrogen thermal compression

Abstract

LaNi 5 was obtained from raw materials by low energy mechanical alloying. Hydriding properties of as-milled intermetallic were improved by annealing. Pressure-composition isotherms showed flat plateaus when annealing temperature was 600 °C, this value is at least 300 °C lower than the synthesis and annealing temperature of standard equilibrium methods. This low energy mechanical alloying – low temperature annealing procedure reduces the number of intermediate stages needed to scale up the fabrication of the intermetallic. After cycling this material in hydrogen, its hydriding properties were studied in the 25–90 °C range. From these results, we propose a one-stage hydrogen thermal compression scheme working between 25 °C (absorption) and 90 °C (desorption) with a compression ratio of 2.5 and a useful capacity of 1.0 mass %.