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研究Gamma等轴NG组织和近片层NL组织的Ti-46.5Al-2Nb-2Cr合金在不同温度和应变率下的力学行为和断裂模式,揭示温度和应变率对不同微观组织的力学行为和断裂特性的影响。结果表明,两种微观组织的TiAl合金均与温度和应变率相关,且具有类似的温度和应变相关性:动载下的强度明显高于静载下的强度,但在高应变率范围内(320-1350s-1)无明显的应变率相关性;韧脆转变温度(BDTT)随应变率的增加而升高;等轴组织的TiAl合金的真应力—真应变曲线中可以看到明显的屈服现象,而近片层组织的屈服现象不明显。在韧脆转变温度以下,随着温度的上升,两种组织的TiAl的断裂方式均由穿晶解理断裂转变为穿晶断裂与沿晶断裂的混和模式,最后转变为沿晶断裂方式。
The mechanical behaviors and fracture modes of Ti-46.5Al-2Nb-2Cr alloy with G-equiaxed NG and near-layer NL were studied under different temperatures and strain rates to reveal the effect of temperature and strain rate on the mechanical behavior and fracture of different microstructures Effect of characteristics. The results show that both microstructures of TiAl alloy are related to temperature and strain rate, and have similar temperature and strain correlations: the strength under dynamic loading is obviously higher than that under static load, but at high strain rate (320 -1350s-1). The ductile-brittle transition temperature (BDTT) increased with the increase of strain rate. The true stress-true strain curve of the isometric Al-TiAl alloy showed obvious yield phenomenon , While the yield structure of near-strata organizations is not obvious. Below the ductile-brittle transition temperature, as the temperature rises, the fracture modes of TiAl in the two kinds of structures are changed from transgranular cleavage fracture to mixed mode of transgranular fracture and intergranular fracture, and finally to intergranular fracture mode.