【摘要】 对GH33镍基高温合金进行大气、氩气和真空环境的750℃拉伸试验表明,合金的中温塑性因氧分压的降低而有显著的变化。环境中的氧促使试样沿晶断裂,导致了中温低塑性。本文进一步对氧导致GH33合金中温沿晶断裂的机制进行了研究,认为在中温拉伸变形过程中,试样的氧化表面首先发生沿晶裂纹,氧沿着裂纹尖端前沿的晶界优先渗入,在应力的促进下与晶界上呈链状分布的Cr₂₃C₆碳化物反应,产生CO气泡,形成裂纹前沿晶界上的空洞,使晶界裂纹迅速扩展而造成沿晶的脆性断裂。本文还对GH37等其他镍基合金的试验结果作了分析,认为上述机制也是适用的。更多还原

【Abstract】 The tensile ductility of a nickel-based superalloy GH33 was studied at 750℃ indifferent environments,i.e.,air,argon and vacuum.It was discovered that the oxygencontent would cause intergranular fracture and low ductility at the intermediatetemperature.Further research has been made on the mechanism of oxygen embrittlement inGH33 alloy.It is proposed that the apparent mechanism is as follows:oxygenpenetrates preferentially along the grain boundaries ahead of the crack tip when thespecimen is tensile tested at the intermediate temperature in air.Promoted by theapplied stress,reaction between oxygen and grain boundary carbide occurs,and producesbubbles of CO to form cavities along grain boundaries,and thus the crack propagates.The above process leads to brittle intergranular fracture of the alloy.Discussions on the test results of alloy GH37 and another nickel-based superalloyhave shown that the above embrittlement mechanism can be more generally applicable.更多还原