Lasers

The discovery of the laser in 1960 was quickly seen to have defence implications. After a review of work in progress overseas, it was decided to establish background research programmes in Australia. By 1962, MRL[51] had begun a programme on high powered lasers, and WRE{52} on low power ones for high precision applications.

The work was a considerable stimulus to the physics research in both establishments. At MRL, solid state and dye lasers were developed; and a carbon dioxide laser was constructed. From 1967, L. E. S. Mathias was the leader, and innovations included construction of a 2 kilowatt continuous power laser, the first reported electron beam-controlled CO₂ laser, the first atmospheric pressure laser, and the first using plasma injection. Much of the work was directed to laser-damage sensitivity of materials, and to laser safety.

The complementary work at WRE, under the leadership of F. F. Thonemann, was on the instrumental use of lasers. Several kinds were built, and experiments conducted on modulation, switching, and frequency multiplication. An early application was the development for the Division of National Mapping of an airborne system (WREMAPS) to measure ground profiles accurately. Later, using frequency doubling to obtain green light from a neodymium laser, they produced a more efficient system called WREMAPS II for the Royal Australian Survey Corps.

High Temperature Alloys

The infant aeronautics industry developed in anticipation of the Second World War had made a significant contribution and at the war's end there seemed every prospect that it would prosper and that aircraft and engines would continue to be designed and built in Australia.

Powerful and efficient gas turbines make extreme demands on materials particularly for hot end components. High-temperature materials problems were acute, even in the Whittle era, where electric element and exhaust valve materials were the best available. Improvements in gas turbine performance have largely followed developments in the nickel and cobalt base alloys.

Australia, through the agency of the Aeronautical Research Laboratories (ARL) and the Defence Standards Laboratories (now Material Research Laboratories) declined this derivative material concept and, opted for an attempt to develop completely new alloy systems, using the best available basic knowledge of alloy developments at that time. The analysis by H. L. Wain and others suggested that binary alloys based on chromium, with additions of such metals as tantalum, tungsten, and molybdenum could enable the gas turbine operating temperatures to be increased considerably.

Since at that time chromium technology was limited to protective electroplating, methods had to be developed to produce and fabricate chromium and its alloys by melting, casting, extrusion, swaging and rolling into useful forms for test purposes. A great concern throughout this work was to develop adequate initial ductility in the chromium alloys and maintain it in service. Chromium, once classed as 'inherently brittle' was shown in the laboratories to be ductile if specific impurity levels and structure were controlled; similar characteristics were developed in chromium alloys. This was a major achievement of the program, even though ductility after service was never as high as engine designers would have liked. Demonstration alloys, the most successful of which contained 2 per cent Ta, 0.1 per cent Ti (to promote ductility) and 0.5 per cent Si (to improve oxidation resistance) were produced in Australia and, under licence in the USA. In Australia, a high temperature turbine was developed and fitted with 53 blades of the new alloy. The disc was forged by Commonwealth Aircraft Corporation, and the special blade blanks were manufactured by Australian National Industries. The blade system operated uncooled up to inlet gas temperatures of 1250°C, which was some 200°C in advance of the then operating systems.

Australian Academy of Technological Sciences and Engineering