摘要  TiA1合金是一种新型轻质的高温结构材料，密度不到镍基合金的50％ ，具有轻质、高比强、高比刚、耐蚀、耐磨、耐高温以及优异的抗氧化性等优点。TiA1合金的全片层组织与其它组织相比，断裂韧性更高，力学性能更好，故目前工程应用上多趋向于选择全片层组织。由于其片层结构的特点采用定向凝固技术控制片层方向可以更好地发挥其潜能，当片层方向与生长取向平行时，可以得到最佳的强度与塑性的综合。已有人通过定向凝固的方法成功的制备出片层方向与生长方向平行的PST，但都致力于研究固液相变的过程而忽视了固态相变的过程。本文希望通过定向凝固的方法调节抽拉速率来获得片层方向与生长方向平行的PST并通过定向热处理的方法来研究固态相变对合金片层取向的影响。60605

毕业论文关键词  TiA1合金    定向凝固   片层取向   抽拉速率  定向热处理 

毕业设计说明书（论文）外文摘要

Title  Study on the Directional Phase Transformation and the Lamellar Orientation of TiA1 alloy

Abstract

TiA1 alloy is a new high temperature structural material with light weight.Its density is 50% less than nickel-base alloy 。It has the advantages of light weight, high specific strength, high specific stiffness, corrosion resistance, wear resistance, high temperature resistance and excellent oxidation resistance.Compared with other structures,  fully lamellar structure of TiA1 alloy has higher fracture toughness and better mechanical properties. So the fully lamellar structure  is always used in the engineering application . Because of its lamellar structure,  its potential can be developed when we control the lamellar orientation with the directional solidification technology . When the lamellar orientation  is parallel to the growth direction,we can get the best strength and plasticity. Someone has successfully prepared the PST with its lamellar orientation  paralleled to the growth direction , but they are devoted to the study of solid-liquid phase transformation while they neglect the process of solid-state phase transformation.We hope to prepare the PST with its lamellar direction paralleled to the growth direction by regulating the running rate with the directional solidification and study the effects of solid-state phase transformation on  the lamellar orientation with the directional thermal treatment.

Keywords   TiA1 alloy   directional solidification  lamellar orientation     the running rate          directional thermal treatment

 目  录

1  绪论 1

1.1  选题意义和课题背景 1

1.2  TiAl基合金定向凝固技术和研究现状 2

1.2.1  TiAl合金相图 3

1.2.2 TiAl合金组织和力学性能 3

1.2.3  TiAl基合金定向凝固 5

1.3 定向固态相变 7

1.4  本实验主要研究内容 9

1.5 本章小结 10

2. 实验过程及分析 10

2.1  实验方案 10

2.2  实验设备 11

2.2.1  受控凝固系统 11

2.2.2  悬浮熔炼炉 13

2.3 试样的定向凝固 14