Abstract: A method for producing hollow diamond tubes by diamond growth using chemical vapor deposition (CVD) techniques. Suitable substrate material, such as tungsten, molybdenum, copper or silicon, typically in the form of wire, having diamond nucleation sites is formed into a helix. The helix is then placed, or moved through, a CVD chamber for deposition of diamond on the helix. Suitable pitch and diameter of helix results in deposition diamond on the helix until such time as the growth surfaces of the diamond fuse to form a hollow diamond tube.

Abstract: An aluminium alloy is provided which consists of 2 to 12% by weight of chromium, 0.2 to 3.0% by weight of iron, the balance being aluminium apart from minor proportions of impurities and incidental elements wherein most of the chromium is present as a metastable solution in the aluminium lattice which contains a precipitate phase of iron rich zones the major proportion of which have dimensions of 200A or less, the presence of large intermetallic particles, particularly at grain boundaries, being at a minimum. This alloy may be produced by an evaporation deposition process.