(哈尔滨工业大学材料科学与工程学院， 哈尔滨 150001)
摘 要: 在77～623 K对淬火态TC4合金进行了热循环试验 ，测定了合金热循环后的硬度，并与623 K时效合金的硬度进行了对比；还观察了拉伸试样断口形貌。结果表明：热应力能加速亚稳相的分解，使合金中的位错密度升高 ，层错和形变孪晶的数量增多；循环温度场作用下淬火态合金拉伸试样断口由韧窝型断裂向韧窝和撕裂棱混合型断裂转变。
关键字: 钛合金 热循环 硬度
（School of Materials and Engineering, Harbin Institute of Technology, Harbin 150001）
Abstract:The thermal cycling tests between 77 and 623 K were performed on the as-quenched TC4 alloy, the hardness after thermal cycling were evaluated and compared with that of the alloy aged at 623K. And fractography was investigated by means of SEM. The results show that thermal stress accelerates the decomposition process of meta phase and makes an increase in dislocation density or amount of deformation twins and stacking faulty. Fractography of the quenched tensile specimen under cycling treatment changes from dimple pattern to mixed fracture with dimple and tear ridges.
Key words: titanium alloy thermal cycling hardness
