In　order　to　investigate　the　effects　of　chromium　on　the　electrical　contact　properties　of　the　Al2O3-Cu/15W　composites,　vacuum　hot-pressing　sintering　and　internal　oxidation　methods　were　employed　to　fabricate　the　Al2O3-Cu/15W　and　Al2O3-Cu/15W5Cr　composites.　The　microstructure　was　analyzed　by　scanning　and　transmission　electron　microscopy.　The　electrical　contacts　testing　was　performed　using　the　JF04C　testing　machine　at　30　V　DC　with　10-30　A　current.　The　effects　of　Cr　on　the　comprehensive　properties,　arc　erosion　morphology　and　welding　force　of　the　electrical　contacts　were　investigated.　The　mass　transfer　mechanism　was　discussed.　It　was　demonstrated　that　the　Al2O3　nanoparticles　pinned　dislocations.　The　diffraction　spots　of　the　Cu　matrix　and　the　γ-Al2O3　disclose　an　orientation　relationship　of　Cu//γ-Al2O3,{020}Cu//{040}γ-Al2O3.　A　typical　arc　erosion　morphology,　such　as　needle-like　and　coral　structures　was　formed,　which　provides　significantly　enhanced　arc　erosion　resistance　of　the　contact　material.　Compared　with　the　Al2O3-Cu/15W　composite,　the　Al2O3-Cu/15W5Cr　composite　has　a　lower　welding　force.　The　two　composites　present　two　distinct　mass　transfer　trends　before　and　after　25　A.　The　final　mass　transfer　direction　of　the　composites　is　from　the　cathode　to　the　anode.　The　Al2O3-Cu/15W5Cr　contacts　have　less　mass　change　under　all　testing　conditions.　©　2019　X.　Zhang　et　al.,　published　by　De　Gruyter.