TC21两相钛合金中斜方马氏体的时效分解  

Decomposition of Orthorhombic Martensite in TC21 Alloy during Aging Treatment

作　　者：何宜柱[1] 张文学[1] 周红伟[1] 卢亚锋[2] 奚正平[2] 

机构地区：[1]安徽工业大学,安徽马鞍山243002 [2]西北有色金属研究院,陕西西安710016

出　　处：《稀有金属材料与工程》2012年第5期800-804,共5页Rare Metal Materials and Engineering

基　　金：国家科技支撑计划项目(2007BAE07B0X);安徽工业大学创新团队项目(0201)

摘　　要：研究了TC21两相钛合金淬火后马氏体在时效过程中的组织结构变化及其引起的强化效应。结果表明:合金淬火后得到交错排列的针状斜方马氏体组织,在300-700℃之间时效4h,α″相的分解次序遵循α″→α″+α→α+β规律。低温时效时首先形核析出针状的初生α相,随着时效温度的升高,初生α相在长大的同时其片层之间析出十几纳米宽、几个微米长的细小次生α相,且β相呈10～50nm大小的颗粒状弥散分布在α相之间,随后的时效过程中次生α相和β相迅速长大,最终斜方马氏体完全分解为α+β混合相。显微硬度分析表明,利用斜方马氏体的逆转变,通过在时效过程中均匀地析出细小的次生α相和纳米级弥散分布的β相可使合金具有明显的时效强化效果,500℃时效4h后,TC21合金的显微硬度比淬火态提高了35%。The phase decomposition of orthorhombic martensite and the age hardening effect in TC21 alloy during aging treatment were investigated in this paper.The as-quenched alloy shows an acicular structure of orthorhombic α″ martensite.The overall decomposition reaction after aging at 300-700 °C for 4 h can be represented by the order of α″→α″+α→α+β.Aging at lower temperature,the acicular α phase firstly precipitated along with the martensite lath.With increasing of aging temperature,the fine precipitated α phase grows rapidly to lath or plate morphology.Then the much finer second α phase,about 10 nm in width and several micrometers in length,and also the densely distributed β phase,about 10-50 nm in size,were identified using dark field micrograph and selected area electron diffraction.Finally the orthorhombic α″ phase decomposed to α+β mixed phase.Significant age-hardening was observed in TC21 alloy,compared with the as-quenched alloy,the microhardness increased by 35 percent after aging at 500 °C for 4 h,the age-hardening can be attributed to the fine second α precipitates and the dispersively distributed β phase formed by the reverse transformation of orthorhombic martensite.

关 键 词：TC21合金 时效 斜方马氏体 硬化 

分 类 号：TG146.23[一般工业技术—材料科学与工程]