The ordering process in Ni,Mo gives rise t om three different classes of interfaces within a single crystal of the basic structure. The geometry of these interfaces and the diffraction effects t o be expected from them are discussed. Evidence for the different classes of interfaces is given. The interfaces resulting from slip are discussed and compared with the observations. Quenched specimens exhibit short range order. A model for short range order in this alloy is presented. Preliminary experiments indicate that quenched Ni3Mo also shows short range order of a similar type as Ni,Mo.Der OrdnungsprozeB in Ni,llo gibt AnlaB zu drei verschiedenen Klassen von Grenzflachen innerhalb eines Einkristalls mit der GrundstruktF. Die Geometrie dieser Grenzflachen und die daraus zii erwartenden Beugungseffekte werden diskutiert. Hinweise fur die verschiedenen Klassen der Grenzflachen werden angegeben. Die Grenzflachen, die aus der Gleitung herruhren, werden diskutiert und mit den Beobachtungen verglichen. Abgeschreckte Proben zeigen Kahordnung. 13in Model1 fur die Nahordnung in diesen Legierungen wird vorgelegt. Vorlaufige Experimente zeigen, daB abgeschrecktes Ni,Mo ebcnfalls eine Nahordnung von ahnlicher Art wie Ni,Mo aufweist.

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Diffusion in inert‐gas bombarded Pt and Al is studied by gas‐release measurements, transmission electron microscopy, and depth‐distribution measurements. It is found that gas release in Pt exhibits three components with temperature ranges of ambient < 500, 500 to 850, and > 850°C of which the range 500 to 850°C coincides with the temperatures of Pt self‐diffusion and in turn leads to the value 57 to 64 kcal/mol for ΔH for Kr‐Pt. By contrast, Al is shown to retain inert gas up to the melting temperatur of 660°C. Transmission electron microscopy of Pt shows that the gas release at 500 to 850°C is accompanied by dislocation loop annealing, while that at > 850°C coincides with the occurrence of bubbles. The tendency of Al to retain gas is found to correlate with the appearance first of bubbles and then, at about 625°C, of large surficial blisters. Depth‐distribution experiments with Pt show that the gas remaining at temperatures where bubbles are present has a deeply penetrating, exponential form, whereas in Al heated above 465°C the gas is mostly concentrated near the surface. The theory of bubble diffusion is finally considered, and is shown to predict bubble motion over the temperature ranges inferred by the other observations, namely 7> 850°C for Pt and > 500°C for Al.

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