摘要
测试了Al-14Cu-7Ce(质量百分数)铸造铝合金在室温至450℃内的高温短时拉伸性能,并采用扫描电镜分析不同温度下试样断口形貌和断裂行为。试验结果表明:温度低于200℃时,强度缓慢下降,且200℃下抗拉强度达到343.4MPa;在200～450℃,强度迅速下降,但450℃下其抗拉强度仍能达到142.5MPa,表明合金具有良好的耐热能力。随着变形温度的升高,合金逐渐由脆性断裂转变为韧性断裂,在250℃下合金表现出混合断裂特征。此外,裂纹萌生都由Al8CeCu4相引发,在应力作用下形成裂纹源,并从Al8CeCu4相内部扩展导致开裂,之后裂纹扩展至基体并与前方裂纹相互连接,最终导致试样发生断裂。
The high temperature tensile properties of Al-14Cu-7Ce（wt% ） casting alloy were tested at room temperature to 450℃. The tensile fracture surfaces and modes of the tensile specimens at different temperature were studied using scanning electron microscopy （SEM）. The results of the high temperature tensile tests show that when the temperature is below 200℃, the strength decreases slowly, while the temperature increases from 200 ℃ to 450 ℃, the strength declines rapidly. The tensile strength at 200 ℃and 450℃ is 343.4MPa and 142.5 MPa, respectively. The alloy has excellent heat resistance. The results of SEM show that with the temperature rising, the fracture mode of the alloy turns from brittle to ductile. At 250℃, AI-14Cu-7Ce casting alloy has a mixed fracture including both brittle and ductile fracture. In addition, the crack initiation was induced by A18CeCu4 phase. The crack source is formed under the stress and the crack extension from internal A18CeCth phase leads to crack, then the cracks expand to the matrix and connects with the front cracks, eventually, the specimens generate fracture.
出处
《热加工工艺》
CSCD
北大核心
2013年第14期36-39,共4页
Hot Working Technology
