Advanced Aluminum Alloy for Aircraft Wheel and Brake Applications

The objective of the proposed SBIR Phase I program is to identify and develop an advanced high strength aluminum alloy for applications in aircraft wheel and brake systems. These applications require material with enhanced property combinations, such as high specific strength, high fracture toughness, high corrosion resistance, high strength retention after cyclic heating during braking events to a temperature as high as 350ºF, high thermal conductivity, and high heat capacity. The major goal is to replace the currently used 2014-T6 Al alloy with a higher strength, better corrosion resistance aluminum alloy and by this way to achieve minimum 5-10% weight savings and/or substantially reduce total life cycle costs of these aircraft components. To achieve this goal, we will explore refinements in the composition of an ultrahigh strength Al alloy (UES patented) to develop a higher temperature equivalent alloy. For this 3 to 4 candidate alloy chemistries will be identified and a laboratory-scale batch of material (about 100 lb of each alloy) will be produced by direct chill casting and hot extrusion. The improved room temperature and elevated temperature strengths of these alloys will be achieved through precipitation strengthening  and dispersoid strengthening. Improved toughness and fatigue resistance will be attained through impurity control, improved microstructural integrity of the cast-and-wrought material and grain refinement by microalloying and special thermomechanical processing. Tensile properties of selected alloys will be determined before and after elevated temperature exposure and corrosion resistance of these alloys will be determined via coupon-level tests. During Phase II, the alloy chemistry of a best performing alloy from Phase I and its processing methods/conditions will be further refined for improved combination of design required properties. Feasibility to scale-up the alloy / processing methods to a component size will be shown by producing a full-scale preform and demonstrating goal properties in critical regions of this full-scale preform. The development of the advanced aluminum alloy with superior ambient and elevated temperature properties can help designers to improve the aircraft wheel and brake performance by decreasing weight and reducing complexity and total life cycle cost. This alloy will also find widespread use in commercial aerospace and transportation industries. BENEFIT: Development of a high-strength, heat resistant Al-based alloy with improved strength, fracture toughness and corrosion resistance, as well as improved strength stability against the elevated temperature exposure, will offer designers a real potential to improve the wheel and brake performance by decreasing the weight, increasing performance, and significantly reducing complexity and cost. Current wheel assemblies consist of two halves which are made from two different alloys. The new material will also find widespread use in other applications, including the commercial aerospace and transportation sectors. Because higher specific strengths translate directly into reduced component mass, a high-strength Al-based alloy will be attractive in any application where component mass and/or volume are constrained, e.g. orbital applications including, but not limited to: bus structures, truss nodes, brackets, hinges, radiator panels and PCB heat sinks. The alloy will also have a significant impact in sustainment, since direct component-for-component replacement will give higher performance in existing systems, e.g. extended component life and reduced maintenance for F-16 aircraft ventral fins. Additional impact will also be felt in the area of unitized design and construction, insofar as increased performance can be met at reduced cost through reducing numbers of parts and fasteners.