Nanostructured ferritic alloy and method of forming

Abstract

An alloy and method of forming the alloy are provided. The alloy includes a matrix phase, and a multimodally distributed population of particulate phases dispersed within the matrix. The matrix includes iron and chromium, and the population includes a first subpopulation of particulate phases and a second subpopulation of particulate phases. The first subpopulation of particulate phases include a complex oxide, having a median size less than about 15 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent. The second subpopulation of particulate phases have a median size in a range from about 25 nm to about 10 microns, and present in the alloy in a concentration from about 0.1 volume percent to about 15 volume percent. Further embodiments include articles, such as turbomachinery components and fasteners, for example, that include the above alloy, and methods for making the alloy.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in part of application Ser. No. 13 / 931,108, filed 28 Jun. 2013.BACKGROUND[0002]The invention relates generally to a nanostructured ferritic alloy. More particularly the invention relates to a nanostructured ferritic alloy having multimodal scale dispersions.[0003]Gas turbines operate in extreme environments, exposing the turbine components, especially those in the turbine hot section, to high operating temperatures and stresses. In order for the turbine components to endure these conditions, they are manufactured from a material capable of withstanding these severe conditions. As material limits are reached, one of two approaches is conventionally used in order to maintain the mechanical integrity of hot section components. In one approach, cooling air is used to reduce the part's effective temperature. In a second approach, the component size is increased to reduce the stresses. However, these approaches...

AI Technical Summary

Benefits of technology

The patent describes an alloy that includes a matrix phase and a population of particulate phases dispersed within the matrix. The particulate phases include a complex oxide and a Laves phase. The alloy has improved properties such as high strength and fatigue resistance. The alloy can be used to make articles such as turbomachinery components and fasteners. The method of forming the alloy involves melting the starting materials, atomizing the melt, and milling the melt in the presence of an oxide. The resulting alloy has a unique structure and improved properties.

Problems solved by technology

Gas turbines operate in extreme environments, exposing the turbine components, especially those in the turbine hot section, to high operating temperatures and stresses.

However, these approaches can reduce the efficiency of the turbine and increase the cost.

However, conventional steels cannot currently be used in high temperature and high stress applications because they do not meet the necessary mechanical property requirements.