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通过高温拉伸、TEM和SEM等手段对2B25-T3511铝合金高温力学性能及组织变化进行研究。结果表明,随拉伸温度升高,合金强度逐渐下降,其中抗拉强度随温度升高而降低的趋势较屈服强度显著;伸长率先升高-降低-略有升高-降低的“M”状变化趋势。在175℃以下,晶粒内基本没有新析出相,合金基体随拉伸温度升高而不断发生软化是强度降低的主要因素,合金基体与相粒子之间的界面弱化以及175℃以上时晶内细小片针状析出相的析出是合金塑性呈现“M”状变化的原因。随温度升高,断口形貌也由沿晶断裂为主逐渐过渡到以高温滑移特征以及基体/沉淀相界面的滑脱为主的韧窝形貌。
The mechanical properties and microstructure of 2B25-T3511 aluminum alloy were investigated by high-temperature tensile test, TEM and SEM. The results show that with the increasing of drawing temperature, the strength of the alloy decreases gradually, and the tensile strength decreases with increasing temperature, which is more pronounced than the yield strength. The elongation increases first, then decreases, then increases slightly, then decreases “Shape change trend. Below 175 ℃, there is almost no newly precipitated phase in the grain. The softening of the alloy matrix along with the increase of drawing temperature is the main factor of the decrease in strength. The interfacial weakness between the alloy matrix and phase particles and the intragranular The precipitation of small pieces of acicular precipitates is the reason why the plasticity of the alloy shows a ”M" shape change. With the increase of temperature, the morphology of the fracture also gradually transitioned from the intergranular fracture to the ductile morphology dominated by the slipping characteristics at high temperature and the slippage of the matrix / precipitation interface.