Near zero thermal expansion in metal matrix composites based on intermediate valence systems: Al/SmB6

This work is focused on the fabrication and characterization of a new type of composite invar materials combining near-zero thermal expansion and functional properties that are important for applications. This is accomplished through the use of particles of SmB6, an intermediate valence system with negative thermal expansion, embedded in Al matrix. The composite based on SmB6-21 vol% was fabricated by hot pressing and was characterized by XRD, optical/electron microscopy, X-ray computed tomography and capacitive dilatometry. The study of thermal expansion revealed that the sample exhibits invar behaviour up to similar to 60 K with a zero value of the coefficient of thermal expansion near 45 K. In comparison to pure aluminum, the temperature range has increased by about 20 K. A quantitative analysis of dilatometric experimental data performed on the basis of widely used theoretical models showed that the thermal expansion of the Al/SmB6 composite was well reproduced within the Turner model.

Automated summary

This study focused on fabricating and characterizing a new type of composite invar material that combined near-zero thermal expansion with functional properties, achieved by embedding particles of negative thermal expansion SmB6 in an aluminum matrix. Experimental data and theoretical models showed that the composite material exhibited invar behavior up to around 60 K, with a zero coefficient of thermal expansion near 45 K, providing an extended temperature range compared to pure aluminum.