,~ study was made of t he creep behavior in tensio n at 300 0 700 0 900 0 and 1 200 0 F of initi, !I y annealed high-purity nickeL Discontinuous flow was dbsel' v~d in ~ach of' the three stages of creep, and . it was affected by ~e mperatu~'e, s train rate, and prior-strain hi stor y. Th e phenomenon of s tram aglllg was especially promlll ent at 300 0 F as manifested by t he attainment of an appreciable creep life in specimens stressed in excess of the te ns ile streno-th at this temperatur~. The experimentall'esults are analyzed in terms of t he past and prese~ t theories of deformat IOn of metals. Stralll hardenlllg, recovery, and t he initiation , propagation , and types of fractures obtamed dunng creep are further evaluated by means of true-stress-truestrain and hardness data obtained at room temperature and by metallographic examination of the fractured specimens.

A main source of high carbon levels in silicon crystals grown from melt under reduced pressures and contained in silica crucibles supported by graphite retainer/susceptor has been identified by thermodynamic analysis. The calculations have been verified by experimental results and the carbon level can be reduced by approximately 50% with the use of molybdenum retainers.The heat exchanger method (HEM) developed to grow large sapphire crystals (1-3) has been extended to the growth of silicon crystals (4). In this method the seed is placed at the bottom of the crucible and the temperature in the melt increases upwards. This suppresses convection that causes temperature and concentration fluctuations at the solid-liquid interface (5).Early experiments indicated that SiC particles were found in crystals solidified by the HEM (6). However, even with the presence of SiC particles, large grains have been grown with limited interface breakdown during solidification. This observation was contradistinct to Czochralski (CZ) growth where interface breakdown due to SiC is followed by twin/polycrystalline growth (7).The basic elements of the HEM and the CZ growth furnaces and the processes are quite similar (heaters, crucibles, insulation, etc.). A silica crucible loaded with the charge and set in a graphite retainer is placed in the furnace. The chamber is evacuated, and after melting the charge crystal growth is achieved. In the HEM process, the chamber is typically evacuated during growth to 0.1 Torr. For CZ growth an argon blanket is used and the chamber pressure can vary from 10 Torr to 1 atm (8). In early experiments with HEM growth it was quite surprising that high carbon concentrations were found in the silicon ingots. The purpose of this paper is to explain the origin of this carbon concentration and to present thermodynamic and experimental results that support the conclusions. Reactions between Graphite and SilicaSilicon, oxygen, and carbon are used in the HEM in the form of silicon melt stock, silica crucibles and graphite furnace parts, and retainers. A thermodynamic evaluation has considered possible reactions between these three reactants and the salient reactions are reported.Carbon has been observed in silicon crystals as silicon carbide, Silicon melt stock and graphite parts are not in direct contact; therefore, the following reactions between graphite and silica crucible were studied 2C + SiO2--> SiC + CO2[1]3C + 3SIO2 --> SiC + 2CO2 + 2SiO[2]4C + 2Si02--> SiC + 3C0 + SiO [3] * Electrochemical Society Active Member.

Short-time tensile tests were m ade at temperatures ranging from 75 0 to 1,700 0 F on high-purity nickel, copper, a 70-percent-nickel-30-percent-copper alloy, and a 70-percenteopper-3 0-percent-nickel alloy. The high-purity component metals and the two alloys were investigated in the initial conditions, as annealed for a uniform grain size, a nd as colddrawn 40-percent reduction in area. The results were affected m a rkedly by variations in the nickel content, temperature, and degree of cold-working. However, the effects of colddrawing at room temperature were obliterated at temp eratures above that of recrystallization.The effects of cold-drawing the 30 % -Ni-70 % -Cu a lloy differe nt amounts a nd of variatio ns in g rain size of the copper on the ten sile properties are evaluated. R es uHs on the tensil e properties of the same annealed materials at low temperat u res are included for completeness.