METALLURGY AND BAILLIEU LABORATORY
F. INDUSTRIAL INVESTIGATION
(23) Workers: G. V. Cullen, R. McPherson and A. J. Casanelia A number of investigations have been undertaken for industrial concerns. Amongst the major projects the following are the most important:
(a) Mineral wool technology— an investigation has been made of the relevant physical properties of slags and of the forma- tion of fibres.
(b) Hot water service and slow combustion stoves —problems asso- ciated with heat resistant cast iron and porosity in non- ferrous castings have been investigated.
(c) The electrical conductivity of Australian aluminium has been determined as a function of deformation in wire drawing.
(d) Some experiments have been made on the roasting and pres- sure leaching of a Tasmanian nickel-copper-ore.
PUBLISHED WORK
1. HEAD, R. B.— The Lower Chlorides of Titanium— Production and Reduction by Electrical Energy. Proc. A'asian Inst. M i n . Me tall. i78 : 21-7 (1956)
2. GUERIN, B. D.—-The Nitroso-R Salt Method for the Determina- tion of Cobalt in Ores. Analyst 81: 409-16 (1956)
3. MUIR, H.— A New Approach to the Properties of Steels. Inst.
Engrs Aust. J. 28: 161-8 (1956)
4. GIFKINS, R. C.— A Mechanism for the Formation of Inter- granular Cracks when Boundary Sliding Occurs. Acta Metal- lurgica 4: 98-9 (1956)
5. Slow Deformation of Metals, particularly at High Tem- peratures. /. Aust. Inst. Metals 1: 134-47 (1956)
6. WOOD, W. A.— Mechanism of Fatigue. Fatigue in Aircraft Struc- tures, pp. 1-19. New York, Academic Press Inc. 1956 (456 pp.) 7. Failure of Metals under Cyclic Strain. International
Conference on Fatigue of Metals, pp. 1-6. London Institute of Mechanical Engineers, 1956.
8. SEGALL, R. L.— Unusual Twinning in Annealed Copper. /. Metals, N.Y. 1: 51-2 (1957)
9. SUITER, J. W.— Preparation of Small Homogeneous Ingots by Argon-Arc Melting. Bull. Inst. Metals 3: 126 (1956)
THESES PASSED FOR HIGHER DEGREES
DOCTOR OF PHILOSOPHY
1. SINHA, H . N . Some Aspects of Titanium Extraction Metal- lurgy
The object of thc work described in the thesis is the development of an electrolytic process for the extraction of titanium and titanium-aluminium alloys. The experi- mental work deals with:
(i) preparation, electrolysis and disproportination of titanium trichloride.
(ii) clectrodeposition of titanium-aluminium allows.
Titanium trichloride has been prepared by the hydrogen reduction of tetra- chloride on hot surfaces and an analysis of theoretical factors such as temperature of reaction, pressure, size, nature and material of the reacting surface affecting the mechanism of the reduction reaction have been studied and the optimum con- ditions worked out. A small laboratory unit for preparing a few pounds of tri- chloride per day has been designed and described. 2-2-2-4 gm. of trichloride per sq. cm. of the reacting surface has been obtained at 1000-1 ioo°C, the consumption of energy being 3-5-4 Kwh.
A semi-continuous method of preparing titanium which involves the preparation and electrolysis of trichloride in thc same unit thus avoiding the problem of handling the reactive compound (TiCl3) and decreasing the chances of contami- nation of the metal produced has been investigated. Also the use of 'hot cathode' has been made to obtain adherent deposits thus being able to make the opera- tion continuous. The hot cathode has been used as a surface of reduction for producing trichloride in situ and obtaining coarse grain metal deposits.
The disproportionation and reduction of trichloride on a hot tungsten filament has also been tried to produce metal in a manner similar to the iodide process of preparing titanium.
The electrodeposition of titanium-aluminium alloys has been carried out from a fused N a C l / A l C l3/ T i C l3 melt. The composition of the alloys varies with the conditions of electrolysis such as potential of electrolysis, trichloride concentration and cathode current density and these factors have been studied. Trichloride has also been produced in situ by using aluminium as a reducing agent for tetra- chloride and it has been observed that the reduction proceeds to the formation of TiAl^ type alloys. Alpha type alloys (15-18% Al) have been produced from a melt containing i o % T i Q3 at electrolysis potentials lying between the decomposition potential of N a C l / A l C l3 and N a C l / A l C l3/ T i C l3 at an average current density of 20-25 a m p / d m2.
2. SUITER, J. W. The Effect of Alloying on the Properties of Titanium at Elevated Temperatures
The investigation was concerned with the effects of alloying on the mechanical properties of titanium in the temperature range 25-6oo°C. Initially thc properties measured were the ultimate tensile stress and thc elongation to fracture. A scries of creep tests was initiated but little information was gained in thc time available.
The first class of alloying additions studied was those which were soluble in a-titanium. This class could be subdivided into:
(i) those elements which dissolved interstitially in the lattice, for example, oxygen. In this class of alloys thc strength at low temperatures increases markedly with increasing alloying content but little change occurs in the strength at high temperatures,
(ii) those elements which dissolved substitutionally in thc titanium lattice, for example, aluminium. In this class of alloys thc strength at all temperatures up to 500°C increases considerably with increasing alloying content but the effect is not so marked at 6oo°C.
A number of ternary solid solutions were also studied and in general the prop- erties of these alloys could be predicted from those of the binary solid solutions.
In the second class of alloying additions, the two types of duplex alloys studied, showed little increase in strength at 6oo°C over the single phase alloys, although at lower temperatures the duplex alloys were considerably stronger. Thc nature of the second phase differed in these two types of alloys. In one, the second
C
hase was an intcrmetallic compound and in the other it was a solid solution ased on thc /3 phase of titanium. It was suggested that the strength of these duplex alloys at 6oo°C could be improved by different dispersion of the second phase.The general behaviour of titanium was interpreted in terms of strain ageing involving the interaction between solute atoms and dislocations. Although many features of the properties of titanium alloys can be explained in this way there
M E T A L L U R G Y A N D B A I L L I E U L A B O R A T O R Y 107 are still some details that cannot be satisfactorily explained. It was concluded that although further improvements in the properties of titanium alloys were pos- sible at temperatures up to 5oo-6oo°C it was unlikelv that the properties would be greatly improved at substantially higher temperatures.
MASTER OF SCIENCE
3. FITZGERALD, L. M . Physical Properties of Steels below thc Yield Point
4. HANNA, G. L. The Extraction Metallurgy of Zirconium — The Electrolysis of its Chlorides
5. MACBRIDE, FIONA The Systematic Ordering of Phase Transforma- tions in the Solid State and Some Aspects of the Transformations Accompanying Order- ing in the Alloy CuAu
6. POLMEAR, I . J. A Study of Ageing in Aluminium-Copper and Aluminium-Copper-Tin Alloys
7. SEGALL, R. L. The Mechanism of the Fatigue of Metals 8. SKATTEBOL, L. Y. A Survey of the Effects of Stress on Magnetic
Quantities