Thermally stable, low resistance Mg2Si0.4Sn0.6/Cu thermoelectric contacts using SS 304 interlayer by one step sintering

•Reliable Mg2Si0.4Sn0.6/Cu contacts were fabricated in one-step hot press sintering using SS 304 interlayer.•Without SS 304 layer, electrical resistivity of Mg2Si0.4Sn0.6 increases ∼60 % due to Cu diffusion during sintering.•Cu/SS 304/ Mg2Si0.4Sn0.6 show specific contact resistance (rc) of 6.1 ± 2 μΩ.cm2 while preserving thermoelectric properties.•SS 304 interlayered contacts maintains rc< 10 μΩ.cm2 even after 15 days annealing at 723 K.