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Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

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Spray deposition processed 6061Al/SiC/Gr hybrid metal matrix composites (MMCs), in their as-extruded condition, have been demonstrated to exhibit both relatively high damping and high elastic modulus, but a reduced strength in comparison with that of unreinforced 6061-T6A1 alloy. In order to explore the possibility of obtaining optimal mechanical properties for potential structural applications, the present work reports on the effect of T6 heat treatment on the damping capacity, elastic modulus, yield, and ultimate strengths of the hybrid MMCs. Both damping capacity and dynamic modulus were measured using a dynamic mechanical thermal analyzer at frequencies of 0.1, 1, and 10 Hz over a 30 to 250°C temperature range. Tension tests were conducted at room temperature on an Instron testing machine. Experimental results revealed that the 6061 Al/SiC/Gr MMCs, following T6 heat treatment, exhibit an optimum combination of room temperature mechanical properties along with an improved damping capacity in the intermediate testing temperature range. The operative damping mechanisms are discussed on the basis of microstructural analyses.

Table 3 -The melt-spinning process was used to perform a systematic study of various elemental compositions, each based on the Fe-based DAR40 composition, with 1, 3, 5, and 7 atomic percent additions of specific elements believed to be beneficial to glass formation or corrosion resistance. Elemental additions investigated included nickel, molybdenum, yttrium, titanium, zirconium, and chromium. ___________________________________ 56 Table 4 -Composition of observed phases in PEA451 as detected by quantitative EDS-analysis.All numbers are atomic percent, with an accuracy of +/-0.5 %. ____________________ 57 Table 5 -Summary of thermal analysis (DTA or DSC) on Fe-based glass forming alloys suitable for spray deposition. ______________________________________________________ 57 Table 6 -Temperature-dependent heat transfer coefficients used in modeling heat transfer during wedge-cast of DAR35. ____________________________________________________ 58 Table 7 -Temperature-dependent heat transfer coefficients used in modeling heat transfer during wedge-cast of LDAR2X7. _________________________________________________ 58 Table 8 -Temperature-dependent heat transfer coefficients used in modeling heat transfer during wedge-cast of LDAR7 (CBCTL1651).________________________________________ 58 Table 9 -A compilation of various amorphous-metal samples, and the measured values of the open circuit corrosion potential (E corr ), the potential coinciding with the anodic oxidation peak (E peak ), the repassivation potential (E rp ), and the penetration rate based upon the maximum passive current density (dx/dt), in concentrated calcium chloride solutions at elevated temperature. _____________________________________________________ 59 Table 10 -A compilation of various amorphous-metal samples, and the measured values of the open circuit corrosion potential (E corr ), the potential coinciding with the anodic oxidation peak (E peak ), and the repassivation potential (E rp ) in Half Moon Bay seawater at various temperatures, ranging from 30 to 90°C _______________________________________ 61 Table 11. A compilation of the results from early cyclic polarization of Type 316L stainless steel, Alloy C-22, HVOF DAR35, HVOF DAR40, and HVOF DAR40X3 in standard 4M NaCl, SCW and BSW test solutions. Note that both SCW and BSW are bicarbonate-type brines. These data were reported at the HPCRM Team Meeting in Key West, held in January 2004. These results were used as the basis of recommending the pursuit of theoretically dense, pore-free materials for testing, so that the effects of alloy composition could be separated from the effects of coating morphology. _______________________ 62 funded by DARPA DSO and DOE OCRWM, and utilizes both theoretical and experimental materials science to develop corrosion-resistant amorphous-metal coatings suiJCF- Table for the desired applications. ___________________________________________________ 65 Figure 4 -The HPCRM Team is multi-institutional and involved three of DOE laboratories (LLNL, SNL, and ORNL), th...