GRAIN BOUNDARY CRACKING IN METALS UNDER STRESS AT ELEVATED TEMPERATURES. Final Report
A study was made of the effect of purification and of a number of metal and oxide additions upon the occurrence of intergranular cracking in brass, copper, nickel, titanium, and zirconium under tension at elevated temperatures. Purification by a variety of means inhibited intergranular cracking in brass, copper, and nickel, and it is suggested that these metals freed of trace impurities, particularly non-metallic impurities, would not exhibit intergranular fracture. Zirconium additions also decreased the frequency of grain boundary cracks in brass and copper, while A/sub 2/O/sub 3/ additions increased the number of cracks. Under a wide variety of conditions, titanium and zirconium of commercial purity were immune to grain boundary cracks and intergranular fracture. This behavior is thought to be related to the high affinity of titanium and zirconium for elements such as oxygen and nltrogen, and/or the ability of titanium and zirconium to dissolve their oxides and nitrides. A few experiments were performed to demonstrate the parallel effect of impurities and additions upon the nucleation of voids during diffusion and the initiation of grain boundary cracks during creep, and the mechanism of crack nucleation by vacancy condensation is discussed. (auth)
- Research Organization:
- General Telephone and Electronics Labs. Inc., Bayside, N.Y.
- NSA Number:
- NSA-16-005716
- OSTI ID:
- 4821998
- Report Number(s):
- NP-10972; TR-61-103-1
- Country of Publication:
- United States
- Language:
- English
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