Effect of ultrasonic vibration on coefficient of friction between a rigid steel die and plastically deformed metal has been studied. The coefficient of friction was measured during a strip-drawing operation with and without application of ultrasonic vibration. The application of ultrasonic vibration during the drawing process substantially reduces the coefficient of friction and die stresses.

Calorimetric measurements on a sample of TiNi (50 at.%) show that the heat-capacity maximum at approximately 87°C represents a higher-order transition. The transition was shifted to lower temperatures each time the material was heated through the transition from slightly above room temperature to about 150°–200°C. The transition enthalpy decreased in three such cycles from 4150 to 3375 J/mole TiNi.

Young's modulus, shear modulus, and internal friction of the intermetallic compound NiTi have been measured as a function of temperature from about −180° to 600°C, in the kilocycle-per-second range. Annealed and cold-worked specimens were used. All the specimens showed the same general pattern, with a minimum in elastic moduli occurring about 70°–140°C, depending upon the particular specimen, and a maximum in internal friction occurring some 50°C below the minimum in elastic modulus. Young's modulus was the same for all the specimens (694 kbar) within experimental error, but the shear modulus of the cold-worked specimens was more than 10% higher than that for the annealed specimens.

No abstract

INDE single-crystal magnesium oxide spheres 1 mm iu diameter were placed on freshly clcaved plates of sodium chloride crystals and were then heated in air a t 7OOOC for times ranging from 1 to 18 hours. After various intervals of time the specimens were withdrawn from the furnace, the spheres were swept away from the plate, and the neck diameter was measured on the stumps left on the plate by the severed necks. It is interesting to note that the necks between the sphercs and the plate always had a squarc shape as one shown in Fig. 1, the edges of the square