Unidirectionally solidified TiTiB and TiTi,Si, eutectic composites

Unidirectionally solidified TiTiB and TiTi,Si, eutectic composites

alloys with and without addition's of iron. Niobium in solid solution in the cobalt matrix caused a fall in the saturation induction and the Curie tem...

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alloys with and without addition's of iron. Niobium in solid solution in the cobalt matrix caused a fall in the saturation induction and the Curie temperature whereas iron raised the saturation induction and lowered the Curie temperature. A minimum in coercive force, measured parallel to the g r o w t h direction, occurred near 8% Fe. (71/3/40) The mechanical response of the Ni-Ni=Nb eutedfie composite: Part 1. Monotonic behaviom"

Hoover, W. R. and I-Iertzberg, R..W.

Metallurgical Transactions, Vol 2, No 5, pp 1283-1288 (May 1971) The deformation and fracture mechanisms of the intermetallic phase, NisNb, were determined and then related to the behaviour of the eutectic composite, Ni-Ni,Nb, in tensile and compressive tests. Metallography and electron fractograph'y revealed that the room temperature ductility of the composite (tensile strains > 11%) was associated with [112] twinning of the Ni.aNb lamellae. T h e amassing of twins eventually led to fracture.

followed by extrusion at elevated temperatures. A composite produced in tlais way with 25 vol% fibres had a tensile strength twice that of pure copper at room temperature and 10 times that of pure copper at tempeoratures between 600°C and 800 C. (71/3!44)

The tensile strength of copper/tungstenfibre-reinforced composite

Bomford, M. J. and Kelly, A. Fibre Science and Technology, Vol 4, No 1, p 1 (July 1971) A study of composites made of copper cast around aligned tungsten wires showed that when allowance is made for the scatter in the strengths of the wires he composite strength follows the law of mixtures. For the case of discontinuous reinforcement the tensile strengths of the composites are found to depend on the stress concentration factors around fibre ends affecting adjacent fibres. (71/3/45)

Unidireefionally solidified Ti-TiB and Ti-TisSi= eut~zfic comlmsit~

Crossman, F. W. and

Yue, A. S.

Metallurgical Transactions, Vol 2, No 6, pp 1545-1555 (June 1971) Unidirectionally solidified eutectic composites were produced of TiB fibres and of Ti~Si, fibres in a titanium matrix, by using induction melting and electron-beam melting techniques. T h e volume fraction of TiB in the Ti-TiB composite was 0.077 and this was found to be insufficient to produce significant reinforcement. T h e TiTi~Ti, composite contained 31 vol% of fibres which caused a considerable improvement in the creep properties and the compressive strength compared with other commercial Ti alloys. (41/3/48)

RESIN MA TRICES

(71/3/,1)

The medumieal response of the Ni-NipNb eutecflc composite: Part 2. Cyclic behaviour

Hoover, W. R. and Hertzberg, R. W.

Metallurgical Transactions, Vol 2, No 5, pp 1289-1292 (May 1971) An investigation was carried into the fatigue crack propagation of the Ni-Ni=Nb eutectic composite compared to that of the AI-AI,N] composite. I n both cases, the high-stress/ low-cycle fatigue resistance is controlled by the fracture resistance of the reinforcing phase whereas the lowstress/high-cycle fatigue resistance. .is controlled by crack propagauon m the matrix. T h e high-stress/low-cycle fatigue behaviour of the Ni-Ni,Nb composite is determined by [112] twinning in the Ni,Nb. (71/3/42) Nickel and cobalt euteetie alloys reinforced by refractory metal carbides

Lemkey, F. D. and Thompsbn, E. R.

Metallurgical Transactions, Vol 2, No 6, pp 1537-154.4 (June 1971) Investigation of alloys of certain refractory metal monocarbides with Ni and Co showed that they could be treated as pseudo-binary eutectics. By unidirectional solidification it was found possible to produce composites of carbide fibres in a Co or Ni matrix. T h e strength of extracted NbC fibres was found to approach the theoretical failure stress, and the NbC fibres produced-a significant improvement in the high-temperature strength properties of Ni. (71/3/43) Sintered copper-base composites reinforced with tungsten fibers

Ivanov, V. E. and Somov, A. I. Soviet

Powder Metallurgy arid Metal Ceramics, No 6, pp 491-494 (June 1970) It was found possible to produce composites of copper reinforced with tungsten fibres, from copper powder and 3 mm long tungsten wire cuttings, by a technique involving compaction

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COMPOSITES December 1971

Thermally induced residual stresses in eutectic composites

Koss, D. A. and Copley, S. M. Metallurgical Transactions, Vol 2, No 6, pp 1557-1560 (June 1971) T h e yield stresses, in tension and compression, of the eutectic composite (CoC0-(Cr,Co),C,, were determined as a function of temperature. At low temperatures the yield stress in compression is higher than that in tension but the difference in the two decreases with increasing temperature and disappears at a l e u t 800°C. Assuming that these effects are due to thermally induced residual stresses, an analysis is presented which predicts the stressrelaxation temperature from the difference in yield stresses at any given temperature. T h e predicted value was shown to agree with the value obtained by observing the thermal expansion behaviour of the composite. (71/3/46)

Transverse properties of unidirectional alumiuium matrix fibrous composites

Lin, J. M., Chen, P. E. and DiBenedetto, A. T. Polymer Engineer-

ing and Science, Vol 11, No 4, p 344 (July 1971) Composites of boron and stainless steel fibres in two types of aluminium alloy were made by filament winding and diffusion bonding and used for a study of the properties of these materials under stresses normal to the unidirectional fibres. Solution treatment and age hardening were found to increase the transverse tensile strength but to have little o r no effect on the transverse tensile modulus. Good agreement between the experimental ,transverse property data and a model calculated by the finite element method and the yon Mises Hencky criterion was obtained. (71/3/47)

Advisory and Component Services plant for production of sheet moulding compound and chopped strand m t

Reinyorced Plastics, Vol 15, No 8, p 186 (August 1971) Advisory and Component Services Ltd have sold their sheet moulding compound production .plants m England, France and Japan and also make plant for the production of glass fibre chopped strand mat. T h e engineering features of both of these plants are reviewed and discussed in short sections concerned with, for example, impregnation, resin feed and general construction. (71/4/68)

Autos offset bigger, tougher role for

plastics

Modern Plastics International, Vol l, No 7, pp 18-22 (July 1971) Current a n d proposed applications of lastics materials, particularly reinreed materials, in the automotive industry are surveyed. T h e main application for reinforced plastics, it seems, will be in the .under-bonnet area ranging from present use of a reinforced rubber timing belt to a possible use in moulded crankcases. (71/4/69)

Capillary materials

extrusion

of

composite

Timothy, T. S. Polymer Engineering

and Science, Vol 1I, No 3, p 240 (May

1971)

Investigations of the theology of unfilled polymer and of polyethylene] glass-beads and. ethylene/propylene. copolymer wRh carbon black filhng showed that the melt fracture mechanisms appear to be the same. In all cases the shear-stress/energy-rate