Transmission Electron Microscopy of Laser Surface Melted Nickel Aluminum Bronze Alloys

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Authors
  1. Bennett, J.C.
  2. Hyatt, C.V.
Corporate Authors
Acadia Univ, Wolfville NS (CAN) Dept of Physics;Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
Nickel aluminum bronze alloys are susceptible to a number of surface sensitive degradation processes during service in marine environments. Surface engineering using laser melting and cladding techniques has demonstrated a potential to substantially enhance performance, however little data is currently available on the microstructures developed in these materials. In this study, the microstructure of a series of experimental nickel aluminum bronze alloys containing from 8 to 12 wt. % Al, 3.8 to 6.5 wt, % Ni, 3.8 to 6.5 wt, % Fe, proportional to 1 wt, % Mn plus additions of Ti and Zr was examined using transmission electro microscopy. The distributions, morphologies and crystal structures of the phases/precipitates present were found to vary significantly with the nominal alloy composition. For quaternary alloys having in excess of 11.30 wt, % Al, the microstructure mainly consists of martensitic Beta' plates containing a high density of small, Fe-rich precipitates of the KIV type. For lower Al contents, the proportion of proeutectoid alpha along the prior Beta grain boundaries and Widmanstaetten alpha within these grains is observed to increase when the Ni/Fe ratio is below unity while Beta appears to be stablized for Ni/Fe ratios greater than unity. TRUNCATED
Keywords
Nickel aluminum bronzes;Laser cladding
Report Number
DREA-SR-1999-162-PAP-22 — CONTAINED IN CA000150
Date of publication
01 Oct 1999
Number of Pages
12
DSTKIM No
CA000172
CANDIS No
511896
Format(s):
Hardcopy;Document Image stored on Optical Disk

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