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
Effect of heat treatment on the fracture behaviour of directionally solidifiedγ/γ′-α alloy
Interet des composites in situ Ni−Mo−Al en raison de leur application possible dans les turbines a gaz. Constitution comprenant des fibres a section carree de Mo enrobees dans une matrice γ' (intermetalllique a base de Ni 3 Al), ou γ (solution solide de Ni)/γ'. Effet de differents traitements thermiques sur le travail de rupture et la microstructure d'un tel alliage de composition ponderale Ni-33 Mo-5,7 Al
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.