Residual stress regulation optimization of plastic and near-zero thermal expansion composite

Realizing high-performance near-zero thermal expansion (NZTE) composites has always been a challenge due to high residual stress and brittleness. In this work, we synthetized multiphase Mn₃Zn_1-xSn_xN with significant negative thermal expansion (NTE) over a wide temperature range (-31.9 × 10⁻⁶ K⁻¹, 265 ∼ 333 K) via spark plasma sintering (SPS). Then, multiphase Mn₃Zn_1-xSn_xN was applied to NZTE Mn₃Zn_1-xSn_xN/Al composites with 0.2 × 10⁻⁶ K⁻¹ from 264 K to 330 K. Residual stress and the NTE behavior change of Mn₃Zn_1-xSn_xN were studied and the mechanical properties of Mn₃Zn_1-xSn_xN/Al was improved by forming coherent interface. As a result, the large lattice constant of the cubic phase in Mn₃Zn_1-xSn_xN was suppressed at low temperatures in composites, thereby weakening the magnetic volume contraction effect during the phase transition process. The composites exhibit excellent compressive plasticity of 12 % even in 50vol.% Mn₃Zn_1-xSn_xN/Al composites. An ideal coherent interface was observed at the interface between Mn₃Zn_1-xSn_xN and Al, which provides excellent load-bearing performance for the composites. The mechanism of NTE performance changes in composites under residual stress and high plasticity revealed by this work can provide guidance for subsequent NZTE research.