航空材料学报

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2020, 40(3)

[Abstract](1606) [PDF 611KB](37)

Abstract:

Microstructure controlling technology and mechanical properties relationship of titanium alloys for aviation applications

Zhishou ZHU, Guoqiang SHANG, Xinnan WANG, Liwei ZHU, Jing LI, Mingbing LI, Yunpeng XIN, Gechen LIU

2020, 40(3): 1-10.

[Abstract](5564) [FullText HTML] (3146) [PDF 1460KB](164)

Abstract:
Because of the variety and complexity of solid-state phase transformation characteristics of titanium alloys, the relationship between their microstructure and performance has always been one of the hot topics in the field of titanium alloy materials science. By adjusting the composition, processing technology and heat treatment process parameters of titanium alloys, the microstructure type and parameters of titanium alloy parts can be adjusted to a certain extent to achieve the best matches in strength, plasticity, toughness, fatigue and fatigue crack propagation rate, etc. In this paper, based on the comparison of four typical microstructure characteristics including equiaxed microstructure, bimodal microstructure, lamellar microstructure, basket weave microstructure and their thermo-mechanical controlling technologies, taking the TC21 titanium alloy, TC4-DT titanium alloy, TC32 titanium alloy and TB17 titanium alloy for aviation use as examples to review the properties of strength, plasticity, fracture toughness, fatigue life and fatigue crack propagation rate, which can provide a reference basis for reasonably choosing microstructure parameters, optimizing properties, stabilizing mass production quality of titanium alloy products.

Recent development in Titanium alloys with high strength and high elasticity

Wenlong XIAO, Yu FU, Junshuai WANG, Xinqing ZHAO, Chaoli MA

2020, 40(3): 11-24.

[Abstract](4996) [FullText HTML] (2915) [PDF 1338KB](92)

Abstract:
Titanium and titanium alloys are important lightweight structural materials in the fields of aviation, aerospace and defense weapons. The low elastic modulus of Ti alloy gives it excellent elastic function, and it is applied to fasteners, springs and other elastic components in aviation, aerospace and other industries. The currently used high-strength Ti alloys exhibit high Young’s modulus that can not fully meet the application requirements. The balance between high strength and high elastic property of conventional Ti alloys needs to be further improved.This paper reviews the current research and development of high strength and high elasticity Ti alloys. Based on the comprehensive understanding of high strength and high elasticity Ti alloys and the existing problems, the composition design method based on electronic theories and the structure design strategy based on phase stability of β-matrix of Ti alloys with high strength and high elasticity is proposed in this paper. The research progress of novel Ti alloys with high strength and high elasticity based on the proposed alloy design strategy is also briefly presented. Finally, the future research direction of Ti alloys with high strength and high elasticity is prospected.

Research progress of dynamic phase transformation behavior of titanium alloy under thermo-mechanical coupling process

Jiangkun FAN, Minjie LAI, Bin TANG, Hongchao KOU, Jinshan LI

2020, 40(3): 25-44.

[Abstract](3231) [FullText HTML] (1993) [PDF 2256KB](82)

Abstract:
Deformation and phase transformation are two major topics in the study of titanium alloy materials. Titanium alloys usually require a series of complex thermo-mechanical treatments to obtain a microstructure corresponding to service performance. Its hot deformation behavior is a typical thermo-mechanical coupling process. Deformation and phase transformation may occur simultaneously and affect each other. It is one of the current research hotspots. However, due to the inevitable existence of dynamic recovery / recrystallization, microstructure fragmentation / spheroidization, a large number of deformation defects, deformation texture, and stress-induced phase transformation during hot deformation, coupled with the changes of the phase transformation kinetics characteristics and the crystallographic mechanism of the variant selection under thermo-mechanical coupling, directly leads to the extremely complicated dynamic phase transformation behavior of the titanium alloy during the hot deformation process, and it becomes quite difficult to reveal its evolution law in depth. This paper summarizes the main characteristics and laws of titanium alloy deformation and phase transformation in view of the dynamic phase transformation behavior of titanium alloy during hot deformation,mainly introduces the research progress of the dynamic phase transformation of the titanium alloy under the thermo-mechanical coupling from the three aspects of precipitation phase morphology characteristics, variant selection mechanism and phase transformation kinetics characteristics, and summarizes and prospects its research and development trend.

Current situation and prospect of TiAl-based alloy modified by carbon nanomaterials

Mingyu WU, Guangbao MI, Peijie LI, Xu HUANG, Chunxiao CAO

2020, 40(3): 45-62.

[Abstract](3025) [FullText HTML] (1960) [PDF 3530KB](61)

Abstract:
Carbon nanomaterials with low density, high strength, high elastic modulus, excellent conductivity and thermal conductivity are the ideal reinforcing phases for TiAl-based alloy. In this paper, the preparation and surface treatment methods of TiAl-based alloy modified by carbon nanofibers, carbon nanotubes and graphene are reviewed. The influence of material and processing on the interface structure and mechanical properties are introduced, and strengthening mechanisms are also summarized. The preparation technology of graphene modified TiAl-based alloy will be the key development direction of future research. The key problems of graphene uniform dispersion technology, interface reaction control and action mechanism in TiAl- based alloy matrix are the difficulties in the research field of this technology.

Research status and development trend of high-strength β titanium alloys

Wei CHEN, Yunxi LIU, Zhiqiang LI

2020, 40(3): 63-76.

[Abstract](3868) [FullText HTML] (1965) [PDF 1905KB](133)

Abstract:
β-Ti alloys have been used in many military/commercial aircraft since 1950s. Their high specific strength, good corrosion resistance, and high formability meet the special requirement of certain structures. Despite a further understanding of the relationship among chemistry, processing, and microstructure, as well as the expanding of performance data base, there is some stagnation in commercialization of new alloys over the past 20 years. This paper reviews the development and applications of β-Ti alloys, and summarizes the important processing parameters for microstructure control. The widely used 5 kinds of high-strength β-Ti alloys are discussed based on their processing-microstructure-property relationship. From the cost and performance perspectives, the challenges and opportunities of β-Ti alloys are identified. Future research will be focused on alloy compositions with more robust processing widows and better performance matching. The integrated computational materials design technology will be a prospect to accelerate the workflow development of chemistry-processing- microstructure-performance for high strength β-Ti alloys.

Application and development of titanium alloy and titanium matrix composites in aerospace field

Shifeng LIU, Xi SONG, Tong XUE, Ning MA, Yan WANG, Liqiang WANG

2020, 40(3): 77-94.

[Abstract](4452) [FullText HTML] (2509) [PDF 1516KB](308)

Abstract:
In recent years, China has continuously strengthened the construction and development of the aerospace industry. While strengthening air military power and accelerating the pace of exploring the space field, the demand for titanium alloys and titanium-based composites with high strength, low density and high temperature resistance has increased. In order to explore the performance of titanium alloys and titanium-based composites in different service environments, this paper reviews the application and development status of titanium alloys and titanium-based composites in aerospace. Through the study of the high-temperature titanium alloys, high-strength titanium alloys, flame-retardant titanium alloys, low-temperature titanium alloy and titanium-based composites, the application and research overview of high-performance titanium alloys and titanium-based composites are described, the problems in the current research are discussed. It is pointed out that the composition control, structural design, and process coupling for titanium alloys and titanium-based composites used for aerospace are the future research directions.

Research progress of atomisation and forming technology of high performance metallic materials

Guoqing ZHANG, Na LIU, Zhou LI

2020, 40(3): 95-109.

[Abstract](2812) [FullText HTML] (1338) [PDF 2053KB](73)

Abstract:
The research and development in liquid metal atomisation and forming technologies of high performance metallic materials with the emphases on gas atomised superalloy powders, spray formed superalloys, powder metallurgy TiAl alloys and spray formed high-speed steels at Beijing Institute of Aeronautical Materials are reviewed. The technology and equipment of argon atomisation and minus atmospheric pressure atomisation (i.e. atomisation in sub-atmospheric pressure atomising assembly) of superalloy powders were established. Major factors contributing to powder oxygen content, particle size and non-metallic inclusions have been identified. A variety of high-purity, fine-grained and high-quality spherical powders of superalloys were produced , which have been utilised in the research and production of hot section components, such as turbine disks in advanced aero-engines. Spray forming technologies of highly-alloyed materials were investigated and developed while taking the key technical issues for making sound performs into process consideration, such as formation and deposition of droplets, densification and shape control, and hot working of preforms. The relative densities of as-deposited performs of superalloys and high-speed steels could be higher than 99.0% after the optimisation of process parameters. Low cost and high performance spray formed superalloys and high-speed steels were developed. Spherical powders of TiAl alloys with high purity and low oxygen content were obtained using the argon atomization techniques, and high performance sheets were subsequently deformed.

Structural stability，microstructure and mechanical behavior of Ti-10V-2Fe-3Al alloy

Lichun QI, Kaichao ZHANG, Wenlong XIAO, Xu HUANG, Xinqing ZHAO

2020, 40(3): 110-117.

[Abstract](2803) [FullText HTML] (1599) [PDF 1045KB](49)

Abstract:
In the present study, Ti-10V-2Fe-3Al (Ti-1023) alloy was prepared by vacuum consumable melting and forging technique. The structural stability, microstructural evolution and mechanical behavior of the alloy were systematically investigated by X-ray diffraction, transmitting electron microscopy and mechanical testing. It is indicated that the structural stability, microstructure and mechanical behavior of Ti-1023 alloy are closely related to the cold deformation and heat treatment. Regardless of the solution treatments in single β phase region (833 ℃) or α + β phase region (753 ℃), double yielding occurs in the stress-strain curves of the alloy. This suggests that the β phases in the alloys with above solution treatments possess low structural stability, and stress induces β→α" martensitic transformation, leading to double yielding behavior. Severe cold rolling deformation and stress/strain induced martensitic transformation gives rise to the refinement of β grains and martensite variants. Since numerous dislocations and grain/phase boundaries induced by severe cold deformation can be used as nucleating sites for the precipitation of α phase, a large amount of fine α phase is precipitated out of the cold rolled Ti-1023 alloy after short aging at 550 ℃, therefore,the alloy exhibits a good balance between strength and ductility.

Effects of heat treatment on microstructure and mechanical properties of TiB_w/TA15（Mo，Si）composites with network microstructure

Junchao ZHENG, Lujun HUANG, Rui MA, Jie BAI, Rui ZHANG, Shan JIANG, Lin GENG

2020, 40(3): 118-126.

[Abstract](2753) [FullText HTML] (1647) [PDF 1166KB](39)

Abstract:
The experimentation adopted low energy ball milling combining, with hot pressing sintering, to design and fabricate 3.4%（volume fraction）TiB_w/TA15(Mo,Si) titanium matrix composites, for investigating the effects of heat treatment on the composites’ microstructure and mechanical properties. Through phase analysis about the composites via X-ray and transmission electron microscopy (TEM), while also analyzing the composites’ microstructure via scanning electron microscope, Several results the experimentation has observed. Firstly, the added TiB₂ generated in-situ synthesized TiBw reinforcement which was distributed around the TA15 titanium alloy powder and formed a network microstructure. Moreover, fine (Ti,Zr)₅Si₃ reinforcement was formed by solid solution and precipitation mechanism and then Mo element was solid solution in β phase after MoSi₂ solution at high temperature. Secondly, solution treatment with 1200 ℃ did not change the microstructure of TiBw neither the characteristics of the network microstructure of the composites, and the matrix was turned into martensite α'. (Ti,Zr)₅Si₃ reinforcement was re-dissolved and transformed to supersaturated solid solution. Thirdly, after aging treatment at 550-700 ℃, the martensitic matrix was decomposed, and the supersaturated silicon element was precipitated at the interface of both α/β interface and the network boundary. The acicular martensite α' was gradually transformed into lamellar (α + β) phase, and the amount of silicide precipitates was gradually increased with the increase of aging temperatures. Later, the experimentation further utilized Instron-5569 universal testing machine to test and analyze the composites’ mechanical properties. The experimental results show that the strength of titanium matrix composites is increased first and then decreased with the increase of aging temperature instead, and the plastic change is opposite to the strength change. The compressive strength of TiB_w/TA15(Mo,Si) composites at 1200 ℃/45 min solution treatment is 1751 MPa, and the strain at break is 6.7%. After 1200 ℃/45 min solution treatment + 600 ℃/90 min aging treatment, the compressive strength of the composites reaches 1900 MPa and the strain at break decreases to 3.6%.

SIF and CMOD for three-point bending beams with arbitrary span-to-width ratios by using analytical weight function method

Dihua TONG, Xueren WU, Xiaochen ZHAO, Wu XU, Benrun HU

2020, 40(3): 127-136.

[Abstract](2256) [FullText HTML] (1131) [PDF 859KB](28)

Abstract:
Stress intensity factors (SIF) and crack mouth opening displacements (CMOD) for three-point bending beams with arbitrary span-to-width ratios (S/W) were calculated by using the Wu-Carlsson analytical weight function for edge-cracked finite-width plate and the analytical solution of un-cracked stress by Filon. Based on the analytical weight function and tabulated SIF and CMOD data for power-law crack-line stresses, SIF and CMOD for general polynomial crack face loadings could be rapidly determined by simple arithmetic. The results obtained for several span-to-width ratios determined by using fundamentally different methods are in excellent agreement with those in literature. A brief discussion is made for calculating cohesive fracture toughness by analytical weight function method. The present study provides a high efficient and accurate method for fracture mechanics analysis of the three-point bending beam with arbitrary span-to-width ratio.

2020 Vol. 40, No. 3