GB/T 23605-2020《钛合金β转变温度测定方法》标准解析

简要介绍了国内外钛合金β转变温度的测试标准,并对其内容进行了对比分析。阐述了已作废标准GB/T 23605-2009存在的问题,详细说明了GB/T 23605-2020的特点和主要内容,供材料检测者和科研工作者参考。     

β型钛合金相变温度的新型金相测试方法

根据钛合金的相变理论,建立了β型钛合金材料相变温度的新测试方法。首先对合金试样进行预热处理,在理论相变温度以上30～50℃保温40min炉冷至650℃后空冷。然后按照GB/T 23605-2009测试相变温度,晶界板条α体积分数小于1%和等于0%的温度区间即为β型钛合金相变温度区间。TC18,TB6,TB3,TB8钛合金相变温度的测试结果表明该方法切实可行,弥补了标准测试法方法的不足。     

钛合金中ω相变的研究进展

钛合金中的ω相及其相变对合金的组织性能影响较大,因此近年来ω相变也成为钛合金研究中的热点问题之一。从ω相的形成、分解、组织形貌以及ω相辅助α形核的角度总结归纳了相关研究报道,对比了相关模型观点的优缺点,阐述了ω相目前仍存在的学术分歧。     

近β马氏体钛合金中的β→ω相变

近β马氏体钛合金的典型热处理制度为固溶时效,该类钛合金在水冷条件下会发生β→ω相变,该相变属于无扩散型相变,相变的形核源于母相(111)晶面的弹性位移重组,而后续时效过程是扩散型相变,其中强化相α相的析出与ω相的体积分数和形貌密切相关。综述了β→ω相变的相变机理和几种典型近β马氏体钛合金中的β→ω相变特点,总结了水冷态近β马氏体钛合金的电子衍射花样的规律。     

α-β两相钛合金棒材常见偏析缺陷分析

对α-β两相钛合金棒材中发现的偏析缺陷进行了分析,并提出了减少或消除偏析缺陷的解决措施。结果表明:α-β两相钛合金棒材中的偏析缺陷一般以亮斑形式存在;偏析可分为间隙元素偏析和主合金化学成分偏析两大类,主合金化学成分偏析又可以分为合金元素贫化、α相稳定元素(主要是铝)富化和β相稳定元素富化3种;棒材中偏析缺陷的产生一般与合金熔炼有关,为了减少或消除偏析,应加强配料过程中间合金选择、电极制备(混布料)、合金熔炼等工艺的控制,并注重各工序间的质量检验。     

热氢化处理对等轴晶α+β相钛合金组织与性能的影响

长期以来,氢在钛合金行为研究中常被看作有害元素,然而在一定条件下氢对钛合金有积极作用,但相关定量研究较少。以氢作为暂时性合金元素对Ti6Al4V合金进行热氢化处理制备了不同氢含量的氢化试样。采用扫描电镜、X射线衍射仪、硬度测试等研究了氢含量对于Ti6Al4V钛合金组织及性能的影响。结果表明:对于氢含量低于0.7%的氢化试样,α晶内均发现片状细化晶粒,随着氢含量的增加,组织晶粒细化越明显,α相含量逐渐减少,β相逐渐增多;由于晶粒组织的改善,其硬度也得到提高,当氢含量为0.6%时,硬度达到最高值383 HV;但当氢含量超过0.7%时,由于氢化物的析出产生较大内应力,导致氢脆,降低了钛合金的力学性能。     

Ti3Al基合金微结构及相变的研究

利用Ｘ射线衍射和透射电子显微镜分析研究了３种不同Ｎｂ量的锻态Ｔｉ３Ａｌ基合金的组织结构２,实验结果表明,含γ（Ｎｂ）量为１０％的合金中,其显微组织由α２相,Ｏ相和Ｂ２相ｒ（Ｎｂ）量为１４％的合金量微组织为Ｏ相和Ｂ２相,而含Ｎｂ量为１７％的合金中显微组织主要为Ｂ２相,其余少量为Ｏ量。     

影响Fe-Mn-Si-Cr-Ni形状记忆合金相变点的因素

研究了变形量和回复退火温度对Fe-14Mn-5Si-8Cr-4Ni形状记忆合金相变点的影响。结果表明：当回复退火温度为673K时，Af点和Ms点都随变形量的增加而显著增加，As点增加较缓慢；303K加热前和加热后合金电阻率之差△ρ也随变形量的增加而增加，可回复变形量随变形量的变化与△ρ的变化是一致的。Fe-Mn-Si-Cr-Ni形状记忆合金的形状回复来源于应力诱发γ→ε马氏体转变及其逆转变；当变形量为10%时，Ms点随回复退火温度的增加而显著下降。     

应用微机测定形状记忆合金的相变点

介绍采用微机系统测定形状记忆合金相变点 ,绘制相变的温度 -时间、电阻 -时间和温度 -电阻曲线 ,实现曲线的自动存储、分析和打印 ,并进行自动数据处理的方法     

NiTi形状记忆合金中异常的多步马氏体相变研究

马氏体相变是NiTi记忆合金具有优良形状记忆效应和超弹性的本质原因.通常,NiTi合金是以一步(B2-B19')或者两步(B2-R-B19')来完成马氏体相变.但在某些条件下,NiTi合金会展现出异常的多步马氏体相变行为.综述了NiTi合金中各种类型的多步马氏体相变行为,并给出了它们出现的条件以及形成的机理.富镍的NiTi记忆合金在中温(400～500℃)时效时会出现三步马氏体相(B2-R-B19'和B2-B19'组成),这是由于NhTi3相在晶界处优先析出所造成的.而在低温(200～300℃)时效时,出现的两步B2-R和一步R-B19'的异常马氏体相变则是由于B2相基体中晶界和晶内的成分不均匀,而这种不均匀性又是由于Ni4Ti3相在晶界处的优先析出所导致的.     

Ti-15Mo-2.7Nb-3Al-0.2Si高强钛合金的相变

利用透射、扫描电镜及Ｘ－射线衍射分析较系统地研究了Ｔｉ－１５Ｍｏ－２．７Ｎｂ－３Ａｌ－０．２Ｓｉ钛合金中亚稳β相在时效过程中的分解特性,并建立了相应的时效动力学转变图。研究结果表明,在５００℃以上时效,β相直接析出次生α相,该温度以下,先析出ω过渡相,再逐步过渡到平衡α相。最后,对该合金的时效硬化效应及硅化物沉淀特性也进行了讨论。     

固溶态Cu-Ni-Si合金的相变动力学

通过测量固溶态Cu Ni Si合金的导电率变化研究了该合金的相变动力学,并由合金导电率与新相体积分数之间的线性关系,确定了该合金固溶及其60%变形态于550℃时效时的相变动力学方程。     

Enthalpy and Temperature of the Titanium Alpha-Beta Phase Transformation

The specific enthalpy and the temperature of the titanium - phase transformation were measured by a pulse-heating system operating in the millisecond time regime. The measurement technique is based on self-heating of a tube-shaped specimen from room temperature to the beta phase of titanium. A comparison between the measured phase transition temperature during heating and cooling of the specimen shows a difference of approximately 20 K. The temperature measured during the heating period is higher than the value obtained from the cooling cycle of the specimen. For the evaluation of the specific enthalpy of the alpha-beta transformation, the specific enthalpy versus temperature function of the beta phase of the heating period was extrapolated to the transition temperature obtained from the cooling cycle (1152 K). A total of 12 measurements on 3 tube-shaped specimens was made, an average value of 89.9 kJkg^–1 was obtained for the specific enthalpy of the transformation. The reproducibility of the measured specific enthalpy at the beginning and at the end of the transformation was 0.5%. The reproducibility of the phase transformation enthalpy as difference between the beginning and the end was 3%. The extended measurement uncertainty (at a confidence level of 95%) is estimated to be ±6% for the specific enthalpy of the transformation and ±6 K for the transformation temperature.     

相图及其在钛电解新工艺和钛合金设计中的应用

相图是材料设计的指导书、冶金工作者的地图和热力学数据的源泉.简要概述了近年来相图计算研究的进展,举例说明了Ti-C-O三元系及其亚二元系相图在钛电解新工艺研究中的应用及Ti-Al相图在钛合金设计中的应用,并在文献中列出了新的可靠的合金和化合物相图的来源.最后指出,进一步测定Ti-C-O三元系中TiC-TiO固溶体的精确固溶范围及其与其它相的相关系对于直接电解TiO2提取金属钛新工艺的工业化有重要意义.     

Creep Induced Phase Transformation in Extruded Zn-Al Alloy

Phase transformation and microstructural change of an extruded eutectoid Zn-Al alloy Zn76Al22Cu2 (wt pct) were investigated during creep testing by using SEM and X-ray diffraction techniques. Creep induced decomposition of a metastable η'T phase and a four phase transformation, α+ ε →T' +η, occurred during the creep testing. Also a microstructural change was observed from a lamellar structure into a spheroidized structure in the rupture part of the extruded alloy. It provided evidence of creep induced phase transformations which occurred in ageing process. The mechanism of creep rupture of the extruded Zn-Al alloy was also discussed.     

Microstructure and Phase Transformation of a Niobium-rich TiAl-based Alloy Containing Boron and Carbon

Microstructure and phase transformation of Ti46Al8Nb0.5B0.2C alloy have been investigated.X-ray diffraction (XRD),optical microscopy (OM),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that as-cast and hot isostatic pressing (HIP) alloy mainly composed of γ and α 2 phase have fully lamellar microstructure with point-like or ribbon-like TiB 2 distributing in lamellar colony or at grain boundary.The mean size of lamellar colony is about 150 and 450 μm for as-cast and HIP alloy,respectively.The lamellar spacing is about 550 and 600 nm for as-cast and HIP alloy,respectively.It has been found that cooling rates and quenching temperatures have significant effect on phase transformation of Ti46Al8Nb0.5B0.2C alloy.When the alloy is treated at 1380℃ for 1 h and cooled from α domain,water cooling leads to complete α→α 2 transformation,oil cooling leads to predominant α→α 2 and part α→γ m transformation,air cooling leads to α→α + γ p2 →L(α + γ) →L(α 2 + γ) transformation,and furnace cooling leads to α→α + γ p3 →L(α + γ) →L(α 2 + γ) transformation.However,when the alloy is treated at 1400℃ for 1 h and cooled from α domain,water cooling leads to predominant α→α 2 and part α→α + γ p4 →γ m transformation,oil cooling leads to α→α + γ p5 →γ m transformation,air cooling leads to α→α + γ p6 →L(α + γ) →L(α 2 + γ) transformation,and furnace cooling leads to α→α + γ p7 →L(α + γ) →L(α 2 + γ) transformation.Microstructural evolution of the alloy during various heat treatments has been examined and the phase transformation mechanisms have been elucidated.Based on the experimental observation,schematic CCT diagrams for the alloy have been given.     

Phase Transformation and Deformation Mechanism of Ti_3Al-base Alloy

The phase transformation and deformationmechanism of the alloy based on composition Ti_3Alwith addition of Nb,V,Mo have been studied by useof transmission electron microscopy (TEM).It hasbeen shown that the orientation relationship ofα_2 phase transformed from β phase is:(0001)α_2//(l10)β,[1210]α_2//[111]β.The present dislocationslip systems in α_2 phase are (1100)[0001] and(1100)<1120>.There also exist α_2 twins whichhave new twin relationship and the twin plane is(2021).     

形状记忆合金相变过程中马氏体含量的表征

形状记忆合金一维热力学本构关系中最重要的部分就是马氏体含量ζ的表征。在近年来应用较多的，以Ｔａｎａｋａ，Ｌｉａｎｇ，Ｂｒｉｎｓｏｎ为代表的三种ζ模型的基础上，提出了一个线性的ζ模型，这个模型与试验吻合性较好，并与Ｌｉａｎｇ等人的模型进行了比较、预测精度相差无几，而本模型却很简单。     

钛合金髋关节假体纯钛/钛合金表面多孔层研究

为获得具有表面多孔层的Ti6Al4V合金髋关节假体,选择不含Cu,Ni等元素的钎料,采用真空钎焊方法获得了纯钛/钛合金表面多孔层.钎焊工艺参数为950℃/30min时,采用φ0.2mm以上粒径的纯钛/钛合金球形粉末,孔径大于100μm,孔隙率6.0%～8.8%,表面多孔层与基体的结合强度大于20MPa.孔径、孔隙率与结合强度均满足人体内植入要求.所采用的钎焊热循环对Ti6Al4V合金股骨柄基体的力学性能和显微组织没有明显影响,符合标准YY 0117.1的规定;生物学评价遗传毒性实验结果为阴性,初步表明钎焊获得的纯钛/Ti6Al4V合金表面多孔层具有良好的生物相容性.