The lower wear rate obtained with bulk alumina femoral hip balls compared to cobalt-chromium alloy balls on ultra-high molecular weight polyethylene is well documented in clinical studies. An alumina coating on a cobalt-chrome component would produce the superior surface properties of the ceramic combined with the desirable bulk properties of the metal. A new technique for forming a blended interface between the alumina coating and cobalt-chrome has been developed. The process uses a high energy ion beam of aluminum impinging on a cobalt-chrome substrate in an oxygen ambient gas to grow the alumina from beneath the metal's surface. Interface thicknesses up to 1200 Angstroms thick have been observed. To date, flat coupons and hip balls, have been coated with coatings 1 micron thick. The coatings were evaluated for polyethylene wear using a laboratory screening tribometer which has been designed to simulate non-linear tracking of the femoral ball on the UHMW polyethylene. The adhesion was measured using a diamond point scratch tester.