Characterization and Properties of Laser Quenched Aluminum Bronzes
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B.H.
Kear,
B.C. Giessen, and M. Cohen,
editors
529
CHARACTERIZATION AND PROPERTIES OF LASER QUENCHED ALUMINUM BRONZES
C. W. DRAPER+, J. M. VANDENBERG++, C. M. PREECE+++, and C. R. CLAYTON-+ + Western Electric, P.O. Box 900, Princeton, NJ 08540; ++ Bell .. Laboratories, 600 Mountain Ave., Murray Hill, NJ 07974; Korrosionscentralen ATV, Park Alle 345, DK-2600 Glostrup, Denmark; !"I State University of New York at Stony Brook, Stony Brook, Long Island 11794.
ABSTRACT Commercial aluminum bronze (Cu-Al-Fe) alloys have been laser quenched with Metastable near surface both continuous and pulsed CO2 laser sources. The quenched regions of approximately 10 Um thickness have been produced. surfaces have been characterized by optical microscopy, SEM, EDX, AES and The behavior of both laser quenched and "as received" glancing angle XRD. conventional surfaces have been tested in both cavitation erosion and In some cases significant differences are observed corrosion environments. and can be rationalized from the microstructural changes accompanying the self quenching.
INTRODUCTION Numerous investigations have shown that laser surface melting (LSM) and the associated rapid self-quenching can be used to produce metastable, Some of the homogenized surface regions on multiphase bulk alloys. investigations have also demonstrated that improved surface sensitive behavior results (1-8). By far the greatest interest has been on ferrous Ni and Ti based alloys have also received considerable alloy systems. attention, but there has been little work published on laser processing of Cu based alloys. Our choice of the aluminum bronze (Cu-Al) family for the present investigation is based on the fact that they are of both scientific and The aluminum bronzes and ternary and quaternary alloys commercial interest. based on them are important commercial alloys finding widespread use, The addition of Al to Cu reduces the particularly in marine applications. thermal diffusivity by a factor of 5 and makes laser surface melting easy to accomplish. Finally, the conventionally prepared Fe-aluminum bronzes contain Thus, both Fe-rich precipitates and a wide variety of matrix phases. transformations requiring extensive liquid state diffusion and diffusionless transformations can be studied simultaneously.
SAMPLE PROCESSING The stable and metastable phases, particularly the martensites, of the Cu-Al system have received considerable attention (9 and refs. therein). Figure 1 presents a vertical section of the Cu-Al-Fe system at 3 wt.% Fe. According to the Unified Numbering System the three alloys studied are Their compositions are C61400: designated C61400, C62400 and C62500. Cu-90.01, Al-6.30, Fe-3.68; C62400: Cu-85.61, Al-I0.43, Fe-3.64 and C62500: Cu-81.94, Al-12.54, Fe-4.09, Mn-l.10. The alternating dash-dot lines in fig. 1 mark the alloys at the stated Al wt. %.
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Fig.
1.
Vertical section at 3 wt% Fe for the phase diagram.
"Cu-Al-Fe equilibrium
Samples were cut from as-received bars, ground and polished to a 600 grit Ultrasonic cleaning
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