The　Fe-1.63Cu-2.17Mn　(wt%)　and　Fe-1.57Cu-2.15Mn-3.23Ni　alloys　were　aged　at　450　degrees　C　to　investigate　the　effects　of　the　addition　of　Ni　on　the　precipitation　process　of　Cu-rich　precipitates.　Their　micro-hardness　and　tensile　strength　in　relation　to　the　microstructures　were　examined.　It　has　been　found　for　the　two　alloys　the　peak　hardness　appeared　at　the　same　ageing　time;　the　hardness　and　strength　of　Fe-Cu-Mn-Ni　alloy　were　higher　than　those　of　Fe-Cu-Mn　alloy　over　the　whole　range　of　aging　time　due　to　the　solid　solution　strengthening　of　Ni　addition;　the　response　of　ageing　treatment　in　the　Fe-Cu-Mn-Ni　alloy　was　smaller　than　that　in　the　Fe-Cu-Mn　alloy,　because　Ni　addition　decreased　the　nucleation　rate　of　Cu-rich　clusters　in　alloy　and　weakened　the　precipitation　strengthening　effect.　After　peak　aging,　Ni　atoms　were　enriched　at　the　precipitate/matrix　interface　close　to　the　matrix　side,　and　promoted　the　segregation　of　Mn　atoms　at　the　interface　close　to　the　Cu-rich　precipitate,　forming　the　core-shell　structure　with　the　core　of　Cu-rich　precipitate,　which　reduced　the　rate　of　growth　of　the　Cu-rich　precipitates　and　the　decline　rate　of　hardness　of　Fe-Cu-Mn-Ni　alloy.