William D. Armstrong

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Aging effects and creep behavior along with microstructure changes in eutectic PbSn and lead-free solder alloy Sn3.9Ag0.6Cu were studied. The room temperature aged Sn3.9Ag0.6Cu alloy continually age-softened due to the growth of relatively large tin-rich crystals. The 180 ºC aged Sn3.9Ag0.6Cu alloy initially age-softened, and the minimum flow strength was(More)
The anterior adhesive system of the oncomiracidium and adult of Merizocotyle icopae (Monogenea: Monocotylidae) were compared. The oncomiracidium has one ventrally placed aperture on either side of the head near the anterior extremity. In the adult, there are three ventrally placed apertures on either side of the head region. Both systems have three types of(More)
The Creep and microstructural changes during creep behaviors of bulk and thin cast forms of Sn3.9Ag0.6Cu were compared. The processing parameters of the thin cast material was selected to result in a very fine microstructure analogous to what occurs in very small size solder electronic interconnections. We found that the thin cast material was less(More)
In this study bulk and thin cast samples were produced with an identical Sn3.9Ag0.6Cu composition. The thin cast material exhibited a much finer as-quenched microstructure than the bulk material with the IMC phase restricted to a thin network. Both the bulk and thin cast materials continually softened during room temperature aging, while both materials(More)
There are at present two different and apparently contradictory theories concerning the role of nonlymphoid cells, particularly phagocytic macrophages, in the initiation of an immune response. One view is that macrophages have an essential role in "processing" antigens and "priming" lymphocytes. It has been suggested that macrophages produce either a(More)
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