Mg-1Ca　samples　were　implanted　with　biocompatible　alloy　ions　Ag,　Fe　and　Y　respectively　with　a　dose　of　2　x　10(17)　ions　cm(-2)　by　metal　vapor　vacuum　arc　technique　(MEVVA).　The　surface　morphologies　and　surface　chemistry　were　investigated　by　SEM,　AES　and　XPS.　Surface　changes　were　observed　after　all　three　kinds　of　elemental　ion　implantation.　The　results　revealed　that　the　modified　layer　was　composed　of　two　sublayers,　including　an　outer　oxidized　layer　with　mixture　of　oxides　and　an　inner　implanted　layer,　after　Ag　and　Fe　ion　implantation.　Y　ion　implantation　induced　an　Mg/Ca-deficient　outer　oxidized　layer　and　the　distribution　of　Y　along　with　depth　was　more　homogeneous.　Both　electrochemical　test　and　immersion　test　revealed　accelerated　corrosion　rate　of　Ag-implanted　Mg-1Ca　and　Fe-implanted　Mg-1Ca,　whereas　Y　ion　implantation　showed　a　short　period　of　protection　since　enhanced　corrosion　resistance　was　obtained　by　electrochemical　test,　but　accelerated　corrosion　rate　was　found　by　long　period　immersion　test.　Indirect　cytotoxicity　assay　indicated　good　cytocompatibility　of　Y-implanted　Mg-1Ca.　Moreover,　the　corresponding　corrosion　mechanisms　involving　implanting　ions　into　magnesium　alloys　were　proposed,　which　might　provide　guidance　for　further　application　of　plasma　ion　implantation　to　biodegradable　Mg　alloys.　(C)　2015　Elsevier　B.V.　All　rights　reserved.