The　correlation　between　preparation　conditions　and　microstructure　as　well　as　magnetic　properties　were　studied　for　Sm(Co0.665Fe0.25Cu0.06Zr0.025)(7)　magnets.　Increase　of　sintering　temperature　from　1468　to　1493　K　promotes　the　amalgamation　of　small　grains　into　big　ones,　resulting　in　an　enlargement　of　average　grain　size　from　10　to　25　mm　and　diffusion　of　Cu　from　inner　grains　to　Cu-lean　grain　boundaries.　As　a　result,　the　demagnetization　curve　squareness　of　the　magnets　improves　substantially,　leading　to　a　remarkable　enhancement　of　the　maximum　energy　product　from　21.3　to　27.1　MGOe.　The　coercivity　of　the　magnets　drops　from　25.3　to　16.0　kOe　at　the　same　time,　which　was　verified　by　the　increase　of　the　average　domain　width　from　1.1　mu　m　in　small　grains　to　2.5　mu　m　in　big　grains.　It　is　therefore　concluded　that　tuning　of　the　preparation　conditions　causes　a　more　homogeneous　distribution　of　Cu,　which　is　crucial　for　the　improvement　of　magnetic　properties.　(C)　2018　Elsevier　B.V.　All　rights　reserved.