制备钛合金件的粉末冶金新技术

钛及钛合金因具有优良的综合性能,在航空航天、军工、民用等领域已得到日益广泛的应用。采用粉末冶金方法生产钛制品不仅成本低,而且产品性能好,因而粉末冶金方法是低成本制备高质量钛舍金件的实用技术。本文介绍了近年来开发的几种制备钛及钛合金件的粉末冶金新技术及其应用状况。     

High-entropy alloys fabricated via powder metallurgy. A critical review

High-entropy alloys (HEAs) have attracted a great deal of interest over the last 14 years. One reason for this level of interest is related to these alloys breaking the alloying principles that have been applied for many centuries. Thus, HEAs usually possess a single phase (contrary to expectations according to the composition of the alloy) and exhibit a high level of performance in different properties related to many developing areas in industry. Despite this significant interest, most HEAs have been developed via ingot metallurgy. More recently, powder metallurgy (PM) has appeared as an interesting alternative for further developing this family of alloys to possibly widen the field of nanostructures in HEAs and improve some capabilities of these alloys. In this paper, PM methods applied to HEAs are reviewed, and some possible ways to develop the use of powders as raw materials are introduced.     

低成本高性能粉末冶金钛合金

粉末冶金是短流程制备低成本、高性能钛及钛合金的有效方法。低成本氢化脱氢（HDH）钛粉可用于制备粉末冶金钛合金制件,但由于受间隙原子含量高、烧结致密度低和微观组织粗大等因素影响,使粉末冶金钛制品的组织性能优势得不到发挥。实验采用氢化脱氢钛粉—冷等静压—真空烧结的技术路线制备了Ti-6Al-4V烧结坯,间隙原子含量低（O<0.16 wt.%, N<0.05 wt.%, H<0.015 wt.%）,具有均匀细小的近等轴?组织,良好的室温拉伸性能（UTS>930 MPa, YS>870 MPa, El>14%）。实验同时表明了HDH工艺制备低间隙原子含量钛粉的可行性,间隙原子含量的增加主要源于粉末及压坯的操作、转移和储存过程。得益于粉末冶金钛合金的细晶和近终成形特点,它无需通过开坯锻造,并且近成型的烧结坯能够提高材料利用率,减少后续热加工变形量及加工道次。因此,以粉末钛合金烧结坯替代锻坯进行后续的塑性加工能够大幅度降低钛合金构件及型材的成本。     

粉末冶金纯钛的热变形本构方程及热加工图研究

采用热模拟试验方法研究粉末冶金纯钛在温度为400~700℃、应变速率为0.001~1 s-1的变形条件下的热变形行为,推导出了粉末冶金纯钛的高温变形流变本构方程,建立基于动态材料模型(DMM)的粉末冶金纯钛的加工图。研究结果表明:粉末冶金纯钛的高温流变应力与变形条件之间的关系可用双曲正弦函数描述,其高温变形激活能为221.23 k J/mol;在高应变速率条件下(0.1 s-1)变形时,材料发生失稳变形。粉末冶金纯钛的最佳变形参数区间为450~550℃/0.001~0.01 s-1和625~700℃/0.001~0.01 s-1。     

汽车用粉末冶金钛合金零件的开发与应用

粉末冶金钛合金具有优良的综合性能,逐步在汽车工业中得到了广泛的应用。简要介绍了 粉末冶金钛合金在汽车零部件中的应用,并对其发展前途加以展望。     

Preparation of porous titanium materials by powder sintering process and use of space holder technique

It is shown that an adapted powder sintering process can successfully prepare a 24.0%-35.5% porous titanium composite using 20μm Ti powder and rice husk particles ranging in size between 250μm and600μm.The phase constituents of the porous Ti composite samples were determined by X-ray diffraction(XRD)pattern sintered at 1250°C.The generation of silicon in the form of a TiSi_2 solid solution,injected into the substrate,illustrates the solid solution strengthening effect.The average grain size of the tested sample and the grain boundary area increase along with the silicon content.This indicates that silicon is dispersed within the green compact of Ti.As the distance from a hole becomes greater,the nanohardness increases until it reaches a maximum hardness of 3.5GPa at approximately 1.5mm.This may be due to the solid solution strengthening of SiO_2.However,nanohardness is 3.3GPa at a distance of approximately 0.5mm from a hole′s edge.The compressive strength is measured to be in the range of 440-938 MPa.The strain reaches 14.8%-16.6% under compression testing.A large number of cleavage steps appear following a fracture.The observed fracture is a brittle fracture.Porous Ti composites with about 36% porosity have promising potential biomaterial applications,specifically related to bone implants and biological bearings.     

Increasing the anticorrosion properties of diffusion chromized porous powder metallurgy iron

Translated from Poroshkovaya Metallurgiya, No. 4, pp. 28–31, April, 1992.     

粉末冶金钛合金SP-700的制备

以Ti、Fe、Mo元素粉及60A140V中间合金粉为原料,通过混料、模压和真空烧结,制备粉末冶金SP-700钛合金,系统研究粉末原料、压制压力及烧结温度等工艺参数对合金相对密度、组织和性能的影响。结果表明,随着压制压力增加,SP-700压坯与烧结体的相对密度均提高;用平均粒度低、氧含量高的Ti粉为原料制备的压坯密度低,而烧结体密度高;烧结温度升高使烧结体密度略微增大。SP-700烧结体组织为晶界和晶内旺层片分布在β基体上;烧结体的性能受粉末原料及烧结温度的强烈影响。与Ti-6Al-4V合金相比,SP-700具有更加细小的组织和更优异的性能。制备SP-700烧结体的最佳工艺以及制品的性能参数为：采用低氧钛粉（0．15％O,平均粒度为73．6μm）,在500MPa压力下压制成形、在1260℃真空烧结5h;相对密度达96．3％,抗拉强度为1008MPa,屈服强度为931MPa,伸长率达4.3％。     

粉末冶金法制备颗粒增强钛基复合材料的研究进展

颗粒增强钛基复合材料因具有高强度、轻量化、耐蚀性和高温力学性能优良等特点被广泛应用于航空航天、汽车工业、医用工程领域。本文介绍了钛基复合材料在国内外的发展概况与研究成果,阐述了钛基复合材料基体组成、增强体形貌及物理性质、增强体引入方式、制备工艺及力学性能等方面,重点讨论了利用不同粉末冶金法制备颗粒增强钛基复合材料的工艺特点及材料特性,并对其进一步研究提出展望。     

粉末冶金生物医用Ti合金的研究及应用现状

Ti及Ti合金具有低密度、高比强度、较低的弹性模量以及优异的耐腐蚀性能和生物相容性,因而成为生物医用材料的首选。本文简要介绍了粉末冶金技术制备Ti及其合金的主要特点及其优势,从粉末准备、成形、烧结、性能4个方面综述了粉末冶金医用Ti合金的研究进展,并总结了目前粉末冶金医用Ti合金的应用状况;针对目前存在的主要问题,分析了粉末冶金医用Ti合金的发展方向及其应用前景。     

粉末冶金50%Si_p/6061Al复合材料的结构与性能

以Si粉和6061Al合金粉末为原料,采用机械球磨-常压烧结工艺制备硅颗粒含量(质量分数)为50%的颗粒增强铝基复合材料,利用扫描电镜和X射线衍射仪分析不同温度下烧结的复合材料结构与物相组成,并测试材料的密度、抗弯强度、硬度及热膨胀系数等性能。结果表明,通过球磨可获得成分均匀的Si_p/6061Al复合粉体。烧结温度为700℃时,50%Si_p/6061Al复合材料仅含少量Al_2O_3杂质,Si相分布均匀,呈半连续骨架结构,Si颗粒与6061Al基体合金结合良好,材料中孔隙的数量和尺寸都最小。在680~750℃温度范围内,随烧结温度升高,50%Si_p/Al复合材料的致密度及抗弯强度先增大后降低,在700℃烧结的50%Si_p/6061Al复合材料具有优异的综合性能,其致密度、抗弯强度、硬度(HB)、热膨胀系数(室温)分别为96.4%,310.8 MPa,225.4和7.43×10~(-6)/K。