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In this paper, the results of preparation and mechanical testing of AlFe7Mn4 alloy are presented. The alloy was prepared by rapid solidification (melt spinning) in the form of thin ribbons. The ribbons were compacted by spark plasma sintering in three different ways-whole, cut into stripes, and crushed into powder in a ball mill. Microstructures of compact materials were observed by scanning and transmission electron microscope. Phase composition was characterized using X-ray diffraction. Rapidly solidified ribbons contained a quasicrystalline phase, but it was transformed to stable phase during compaction independently on the ribbons pre-treatment. Bulk material prepared from whole ribbons exhibited anisotropy of microstructure and mechanical properties. Material prepared from cut stripes showed also slight preferential orientation of ribbon pieces. Crushing of ribbons in a ball mill led to contamination of the alloy powder and to deformation strengthening of bulk material.

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We describe a variable path acoustic interferometer for use at cryogenic temperatures. Movement is enabled without mechanical coupling via two piezoelectric bimorphs wired and mounted in a manner that preserves the parallelism of two ultrasonic transducers that define the acoustic path. A certain degree of in situ alignment can also be accomplished. Path length sweeps from 0 to 180 μm have been made at cryogenic temperatures and preliminary sound velocity measurements in liquid He4 and gaseous He3 near 4 K are presented which agree well with past measurements.