摘要高温合金是高度合金化的合金，基体组织单一，机械强度优良，耐热蠕变变形，具有良好的表面稳定和使用可靠性，是国家安全和经济建设中至关重要的物资材料。

本文主要通过运用热处理炉、金相制样设备、蔡司显微镜等基础研究设备，简单的探究热处理制度对镍基高温合金U720Li的微观组织和硬度性能的影响。

经过热处理、金相制备、金相组织拍摄等一系列实验和数据分析得出：（1）随着固溶温度的提高，奥氏体基体组织粗化，但晶粒尺寸未发生异常长大；（2）固溶处理温度对γ’相影响显著，温度升高过程中，晶界处的γ’相发生溶解。晶内γ’相析出，并发生明显的形态变化，由颗粒状向立方体状转变；（3）合金中的γ’相析出数量和形态，对合金硬度改变作用效果明显。硬度随着合金固溶温度的升高而增大，在950℃出现转折形成峰值，在970℃时合金的硬度降低。87188

毕业论文关键词：镍基高温合金；固溶处理；组织性能；γ’相

Abstract Superalloys, or high-performance alloy, is an alloy that exhibits several key characteristics: Single matrixorganization，excellent mechanical strength, resistance to thermal creep deformation，good surface stability and using reliability。 It is vital materials to national security and economic construction。 

In this paper, the effect of heat treatment on Microstructure and mechanical properties of Ni base superalloy U720Li has been studied by using some sample preparation equipments: heat-treating facility metallographic, Cai Si microscope, scanning electron microscope。

After a series of experiments such as heat treatment, Metallographic Preparation and metallographic structure, we can get the results：（1）With the increase of the solid solution temperature, the austenite matrix is coarse。But the abnormal growth is not occurred, and the heat treatment temperature can be more than 1000 ℃。（2）Solution treatment temperature has the significant affect on the γ 'phase。in the process of the temperature rising, γ 'phase in the grain boundaries dissolve。 Intragranular γ' phase separate out and there are no obvious morphological changes, and the circular particle has a transition to the cubic phase。（3）The quantity and patterns of γ ' phase significantly affect the hardness of Superalloys。 The hardness of Superalloys increases with the rise of solid solution temperature。 There will be a transition and it can reach the peak of the hardness at 950 ℃。 But the alloy hardness is lower at 970℃。

Keywords: Nickel-based superalloy; solution treatment; microstructure and properties; γ 'phase

目 录

第一章  绪论 1

1。1 发展历程 1

1。2 应用领域 2

1。3 镍基高温合金的成分、组织及其性能 4

1。4 合金元素在镍基高温合金中的作用 6

1。5 高温合金的热处理 8

1。6 高温合金的强化机理 8

1。6。1 固溶强化 9

1。6。2 第二相强化 9

1。6。3 晶界强化 9

1。7 本文的研究意义、目的和内容 10

第二章  实验材料、设备及方法 11

2。1 实验设备 11