Ag-Mg　alloy　is　used　as　a　dynode　material　in　electron　multiplier　tubes　due　to　the　high　secondary　electron　yields　(delta)　of　the　surface　of　MgO　film.　However,　MgO　film　is　readily　degraded　under　strong　electron　or　ion　bombardment,　which　results　in　a　decrease　in　the　lifetime　of　devices.　In　this　study,　alumina-containing　MgO　films　of　-50-150　nm　were　developed　on　a　Ag-2Mg-2Al　alloy　(silver　alloy　containing　2　wt　%　Mg　and　2　wt　%　Al)　after　a　thermal　activation　process　performed　at　500-600　degrees　C　under　low　oxygen　pressures　of　5.0-20.0　Pa.　Auger　electron　spectroscopy　and　X-ray　photoelectron　spectroscopy　analyses　reveal　that　the　film　consists　of　a　thin　layer　of　pure　MgO　and　a　relatively　thicker　layer　of　alumina-containing　MgO　located　beneath　the　top　MgO　layer.　The　alumina-containing　MgO　film　exhibits　high　delta　value　of　7.7　at　a　primary　electron　energy　of　580　eV　and　a　much　better　stability　under　energetic　electron　bombardment　than　pure　MgO　film　on　Ag-Mg　alloy.　Alumina　has　higher　bond　dissociation　energy　than　MgO,　and　the　presence　of　alumina　in　the　film　contributes　to　mitigating　the　dissociation　of　the　MgO　film　under　electron　bombardment.　The　Ag-2Mg-2Al　alloy　with　alumina-containing　MgO　film　is　a　promising　candidate　as　a　dynode　material　for　electron　multiplier　tubes.