Central South University

Zuming Liu

Quan Li

Boyun Huang

Xueqian Lv

Kai Peng

Bing Wei

Fan Zhao

Bizhong Nong

Yake Ren

Yongkang Ai

Bin Cao

Xu Zhou

Sizhe Lu

Shiqi Chen

Yang Guo

Pengfei Su

Mengmei Ma

Qinglong Duan

A method for preparing a nano-phase strengthened nickel-based superalloy using micron-scale ceramic particles is provided. In the method, a nickel-based superalloy is used as a matrix, and one or more of TiC, TiB, WC and AlOare used as a strengthening phase. A ceramic particle raw material used as the strengthening phase has a particle size of 1-5 μm and is added in an amount of 1-5 wt. %. A nickel-based superalloy composite powder having homogeneously distributed nano-scale ceramic is prepared by mechanical milling. A nano-scale ceramic phase strengthened nickel-based superalloy is prepared by 3D printing technology, which has a homogeneously distributed nano-scale ceramic phase and excellent mechanical properties.

Method for preparing nano-phase reinforced nickel-based high-temperature alloy using micron ceramic particles

A preparation method for an iron-based alloy powder EBSD test sample includes the following steps: surface electrolytic activation of an iron-based powder; ultrasonically cleaning the powder, and drying the powder to obtain a surface activated powder; adding the surface activated powder to a chemical embedding solution for ultrasonic dispersion; after the ultrasonic dispersion, performing a plating process; then heating to 80-92° C. for chemical reaction to prepare an iron-based alloy bulk which coated with nickel. The plating process is as follows: still standing, stirring, and repeating the still standing is taken as a cycle, and at least one cycle is performed to complete the plating process. Then grinding and electropolishing are done to the obtained iron-based alloy bulk coated with nickel to obtain the iron-based alloy powder EBSD test sample.

Preparation method for iron-based alloy powder EBSD test sample

A method for preventing cracking of nickel-based superalloy fabricated by selective laser melting (SLM) belongs to the field of additive manufacturing (AM). The method of preparing an as-built part with a high density, no crack defects, and good mechanical properties includes: reducing the content of elements Zr and B forming low melting point phase in a nickel-based superalloy, adjusting the total content of Al and Ti in the alloy to 4.5 wt % or below, and combining with the control of special SLM process parameters. The new method has the advantages of a reasonable component design, a simple preparation process, and good performance of the as-built part, and therefore is suitable for large-scale application.

Method for preventing cracking of nickel-based superalloy fabricated by selective laser melting

A method for preparing a nano spherical oxide dispersion strengthening phase using a micron oxide is proposed for the first time. First, a micron oxide is used as a raw material to prepare a nano oxide with a completely amorphous structure/matrix alloy composite powder by mechanical ball milling in stages. In the first stage, ball milling is performed, causing the oxide to break and transform in structure, and achieving nano-sizing and completely amorphization, to prepare a composite powder with a completely amorphous structure nano oxide uniformly distributed in the matrix alloy powder; and in the second stage, the composite powder obtained in the first stage and the remaining matrix alloy powder are uniformly mixed by ball milling. Then, the uniformly mixed powder is sequentially subjected to hot forming, hot rolling, and heat treatment, to obtain a nano spherical oxide dispersion strengthened alloy.

Method for preparing nano spherical oxide dispersion strengthening phase

The present disclosure relates to the field of additive manufacturing and superalloys, particularly to a method for eliminating cracks in René 104 nickel-based superalloy prepared by laser additive manufacturing. For solving the problem that cracks are easily generated during laser additive manufacturing of René 104 nickel-based superalloy with high content of Al and Ti (Al+Ti>5 wt. %), generation of large-size cracks inside a fabricated part is suppressed by means of designing laser forming parameters and a partition scanning strategy; then stress relief annealing is performed to completely eliminate residual stress inside the fabricated part; and a spark plasma sintering process is performed to eliminate cracks inside the fabricated part and suppress the growth of grains during the sintering process.

Method for eliminating cracks in rené 104 nickel-based superalloy prepared by laser additive manufacturing

A multi-scale and multi-phase dispersion strengthened iron-based alloy, and preparation and characterization methods thereof are provided. The alloy contains a matrix and a strengthening phase. The strengthening phase includes at least two types of the strengthening phase particles with different sizes. A volume of the two types of the strengthening phase particles with different sizes having a particle size less than or equal to 50 nm accounts for 85-95% of a total volume of all the strengthening phase particles. The matrix is a Fe&#x2014;Cr&#x2014;W&#x2014;Ti alloy. The strengthening phases include crystalline YOphase, Y&#x2014;Ti&#x2014;O phase, Y&#x2014;Cr&#x2014;O phase, and Y&#x2014;W&#x2014;O phase. The characterization method comprises electrolytically separating the strengthening phases in the alloy, and then characterizing by using an electron microscope. The tensile strength of the prepared alloy is more than 1600 MPa at room temperature, and is more than 600 MPa at 700&#xb0; C.

Multi-scale and multi-phase dispersion strengthened iron-based alloy, and preparation and characterization methods thereof

An oxide dispersion-strengthened (ODS) iron-based alloy powder and a characterization method thereof are provided. The alloy powder comprises a matrix and strengthening phases. The strengthening phases include at least two types of strengthening phase particles with different sizes, wherein a volume of the particles with a particle size of less than or equal to 50 nm accounts for 85-95% of a total volume of all the strengthening phase particles. The matrix is a Fe&#x2014;Cr&#x2014;W&#x2014;Ti alloy. The characterization method of the ODS iron-based alloy powder comprises separating the strengthening phases from the powder matrix through electrolysis, and analyzing and characterizing the strengthening phases using an electron microscope.

Oxide dispersion-strengthened iron-based alloy powder and characterization method thereof

The invention relates to a method for eliminating hollow defects in atomized superalloy powder, and pertains to the field of powder metallurgy materials. A ball-milling processing is conducted on the atomized alloy powder to eliminate the hollow defect, obtain solid powder and increase powder utilization efficiency. By controlling mill ball diameters, mass ratio of mill balls with different diameters, mass ratio of ball to powder and ball milling time, a multi-directional impact on the powder is achieved, thereby control powder shape and obtain solid spherical powder. The invention eliminates powder hollow defect by using ball milling process and equipment. This invention with high powder utilization efficiency, short ball milling time and simple operating process, can be used for large-scale preparation and application.

Growing community of inventors

Hunan, China

Zuming Liu