Open AccessEnergy-filtered imaging of precipitates in FeCuN alloys
Author(s) -
Philip M. Rice,
Roger E. Stoller,
James A. Bentley
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/81052
Subject(s) - materials science , precipitation , alloy , microstructure , transmission electron microscopy , metallurgy , embrittlement , precipitation hardening , hardening (computing) , phase (matter) , crystallography , composite material , chemistry , nanotechnology , physics , meteorology , organic chemistry , layer (electronics)
The microstructures of a series of model ferritic alloys are being characterized by transmission electron microscopy (TEM) techniques. The alloys have varying concentrations of Cu (0 to 0.9 wt%), N (5 to 120 appm), and other solutes to allow a systematic study of the effects of various elements on embrittlement. The first step in this process is the characterization of the alloys in their as-received state: solution treated at 775 C for 17 h, quenched in a salt bath at 450 C for 180 s, and subsequently air cooled. The imaging portion of this initial study is complete; however, several questions about the chemical content of many of the precipitates remain unanswered. To study the affect of Cu precipitation on the hardening of the alloys, a 0.9 wt% Cu alloy was annealed at 550 C for times up to 15 h. The Cu precipitates that form undergo a phase change from bcc to a faulted fcc (9R) crystal structure when they are about 6 nm in diameter. These fcc precipitates have been well characterized by conventional TEM techniques for these alloys. However, the smaller bcc Cu precipitates