Metallurgical operations at elevated temperatures, such as those that involve solidification and/or mechanical deformation, can be critically influenced by the thermal stresses and strains that result from expansion and contraction of the material as a function of temperature. With the increasing use of computer-based process models for these operations, there arises a greater need for quantitative data on the thermal expansion coefficient of the relevant alloy at the temperatures involved. After briefly reviewing some existing sources of data for this property, the various techniques for its measurement at elevated temperatures are then described. These include mechanical dilatometry, optical imaging and interference systems, x-ray diffraction methods and electrical pulse heating techniques. Finally the implications, for process modelling, of the available data and measurement techniques are discussed.

Comprehensive trials have established that latent fingerprints can be rendered partially or totally unidentifiable during print development by the following: (a) ridge smearing, which depends on the type and age of the latent print and also on the type of brush and brushing procedures used, and (b) overpowdering and/or overbrushing of the print. These causes of pattern obscuration are discussed in terms of their implications for fingerprint development procedures, since up to 10% of prints developed at crime scenes can be difficult or even impossible to identify.

Fine flake powders, having flake diameters ranging from 50 to 1 μm and stearic acid/powder ratios varying from 0 to 50 weight percent, were produced by laboratory-scale milling of aluminum, zinc, copper, and iron powders. The effectiveness of these flakes for detection of latent fingerprints was then assessed by comparing the print qualities obtained when using these flake powders with those achieved using commercial aluminum, commercial black, and commercial dark magnetic dusting powders. While the commercial aluminum powder was found to have an average flake diameter and stearic acid level close to the optimum values required to obtain bright fingerprints, several potential avenues of development were identified which could lead to the commercial availability of superior black powders.

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