Achievement of Zero Thermal Expansion Covering Room Temperature in the La(Fe,Al)13-Based Bulks with Reduced Annealing Time

NaZn13-type LaFe13-xAlx compounds attract considerable attention because of their isotropic zero thermal expansion (ZTE). However, there still exist three open questions: How to obtain a bulk sample, in which α-Fe phases with uniform size are homogeneously distributed in the NaZn13 matrix? How long the formation of the NaZn13 phase costs? And, how to enlarge the ZTE temperature region to room temperature? Facing these questions, we adopt copper-mould casting to prepare ZTE LaFe10.3Al2.7 sheet in this paper. The rapid cooling rate provided by copper-mould is helpful to make the α-Fe phases have similar size and homogeneously distributed. Based on this method, the annealing time during which the NaZn 13 phase forms can be shorten to be 2 days. Moreover, Co is added in the composition and the ZTE temperature region is successfully enlarged to room temperature. Our results provide a strategy to design the LaFe13-xAlx bulks with ZTE reaching room temperature