An Aluminum Alloy with Ultrahigh Thermal Stability at 250C

D. Weiss, O. Rios, R. Ott
Eck Industries, Inc.,
United States

Keywords: aluminum, alloys, cerium

Summary:

Most aluminum alloys loose strength at operating temperatures above their aging temperatures of 180-200C. Even alloys containing elements such as Zr, Ni or Sc that form precipitates that are resistant to coarsening can loose strength since the amount of these elements are necessarily limited to maintain the ability to process or to prevent the formation of undesirable intermetallic phases. The authors have developed an Al-Ce-Cu alloy that maintains its room temperature strength after long exposures to temperatures up to 250C. This is done by controlling the Ce-Cu ratio to develop the formation of compact Ce-Cu phases while at the same time leaving some Cu available for additional strengthening via solution and precipitation reactions. The precipitates that form are resistant to coarsening. The strength of the alloy and its high temperature stability can be tailored to specific applications through the modification of the Ce-Cu ratio and by increasing or decreasing the amount of Ce and Cu used. The heat treatment used is at a lower temperature and a shorter time than that specified for most aluminum alloys. This reduced heat treat cycle coupled with the use of alloying elements that are abundant and inexpensive enable this low cost, premium alloy. Production level foundry experiments demonstrated excellent fluidity, resistance to hot tearing and a short solidification range. The alloy is being further developed for use in additive manufacturing, extrusion, forging and plate production, as well as the base for aluminum metal matrix composites.