Effect of Cu particles on phase transformation of spark plasma sintered silicon nitride

•Create a conductive path during the SPS process of Si3N4.•Cu particles promote the growth of elongate β–Si3N4 grains during the SPS process.•Cu particles enhance α to β phase transformation during the SPS process of Si3N4.

Copper/silicon nitride ceramic composites containing 3 and 6 wt% Cu particles were prepared by spark plasma sintering (SPS), having a significantly higher α – β transformation ratio in comparison to the monolithic Si3N4(β: α ratio is 52.6:47.4), with the highest β: α ratio of 84.3:15.7 when the content of Cu is 3 wt%. And the result was attributed primarily to the effect of Joule heating on the solution re-precipitation mechanism, due to the conductive path created by molten copper during SPS process.