Precipitation in a Ni–Al–Mo Directionally Solidified Eutectic Composite
The most recently developed high temperature materials are known as in-situ composites or directionally solidified eutectics. Since the composites are formed during solidification, they have excellent morphological stabilities up to near their melting temperatures. The Ni-Al-Mo system has received the greatest attention for recent several years(1)~(3) since the alloy is expected to form a structure consisting of ductile α-Mo fibers aligned in aductile γ+γ' matrix†. However variations in microstructures and the resultant strength by thermal treatments have not been investigated in earlier papers(1)~(3). In a separate paper(4) the present authors have reported the detailed microstructural analysis of as-grown composite and the microstructural and strength variations of the composite due to quenching from high annealing temperatures. The present paper describes the microstructural changes occurring during ageing of a Ni-12.7at%Al-21.6at%Mo alloy composite after quenching from 1533K studied by transmission electron microscopy
On short range order and micro-domains in the Ni4Mo system
Electron diffraction and field ion microscopy have been used to investigate the nature of short range order in as quenched Ni4Mo. The results indicate that the as quenched state consists of an assembly of micro-domains possessing the six orientational variants of the Ni4Mo superstructure. The 1120 diffuse peaks have been attributed to the occurrence of non-conservative anti-phase boundaries within the micro-domains. A similar argument is used to account for the occurrence of 1120 peaks in the disordered α-phase at other compositions in the NiMo system.
Professor Penck's Bluff: Geography, Espionage and Hysteria in World War I
Abstract This article considers the image of geography during World War I through a discussion of newspaper controversies about the pre‐war activities of German and British geographers. Early in the war, Sven Hedin and Albrecht Penck, renowned geographers whose achievements had been widely celebrated by the British geographical establishment, were named in the media as enemy spies whose supposedly disinterested scientific inquiries in Britain and the Empire had masked their real intention to pass sensitive information to the German High Command. British geography stood accused of collusion with enemy ‘super spies’. This article examines how Britain's geographical community, represented by the Royal Geographical Society, sought to defend the discipline's patriotic virtue and head off a full‐scale media witch‐hunt. In so doing, the article comments on the media's role in shaping the image of geography and on geography's place in public debates about the sanctity of the national space.