temperature increased with increasing oxygen concentration. Grain growth obeyed the growth law or where D is the mean linear intercept grain size at time t, D0 the initial grain size, k'0 a constant and Q the activation energy for grain growth. The value of Q decreased from 52.8 to 44.8 kcal/g-atom with increase in oxygen concentration. Empolying Cahn's impurity dragging theory, the activation energies for the migration of solute-free boundaries and of oxygen atoms in alpha titanium were calculated to be 56 and 37 kcal/g-atom, respectively. (Received July 31, 1972)

temperature increased with increasing carbon content. Grain growth obeyed the growth law or where b is the mean linear intercept grain size at time t, D0 the initial grain size, k0' a constant and Q the activation energy for grain growth. The value of Q decreased from 52.8 to 46.7 kcal/g-atom with increase in carbon content. Employing Cahn's impurity dragging theory, the activation energies for the migration of solute-free boundaries and of carbon atoms in alpha titanium were calculated to be 56 and 42 kcal/g-atom, respectively.

of temperature, strain rate and carbon in interstitial solid solution on the yield and flow stresses were studied in the tem-10-6 dynes and x*0 = 1.3b, which are in accord with the thermally activated overcoming of interstitial carbon atoms by dislocation as the rate controlling mechanism. (Received April 6, 1973) Carbon atoms as well as nitrogen and oxygen atoms, which are found in interstitial solid solution, strengthen titanium at low temperatures. Their relative effectiveness in raising the flow stress of titanium is reported to have the ratios of nitrogen, oxygen and carbon as, for example, 2.0:1.0:0.75 by Conrad(1). These interstitial solutes influence mainly the thermal component of the flow stress, the effect being larger as the temperature is decreased.To establish the separate effects of nitrogen and oxygen on the flow stress of titanium, the present authors have prepared Ti-N and Ti-O alloys by starting with high purity material and doping with various amounts of nitrogen and oxygen and have identified the mechanism of strengthening by deriving the thermal activation parameters (2)(3). As a followup, a series of Ti-C alloys were prepared by starting with the same high purity titanium and doping with various amounts of carbon and the effect of carbon on the mechanical behavior of titanium at low temperature was investigated.

The effects of temperature, strain rate and oxygen in interstitial solid solution on the yield and flow stresses at low nism. The effect of interstitial oxygen atoms on the thermal component of the flow stress increases with decreasing temactivated overcoming of interstitial oxygen atoms by dislocations as the rate controlling mechanism.

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