阅读说明：本技术 一种针状共晶增强的生物Zn-Al-Sn合金及其制备方法 (Needle-shaped eutectic-enhanced biological Zn-Al-Sn alloy and preparation method thereof ) 是由 高成德 帅词俊 王丽 于 2019-08-30 设计创作，主要内容包括：本发明涉及一种针状共晶增强的生物Zn-Al-Sn合金及其制备方法。所述生物Zn-Al-Sn合金中Zn的含量为90-92％,Al的含量为7％,Sn的含量为1-3％。其制备方法为：按设计组份取各原料,球磨混料；然后采用SLM技术制备合金。本发明利用Zn和Sn能够形成针状共晶的特点,制备随机取向并均匀分布的针状共晶组织,能够增强基体的承载能力,而且凝固过程中Sn能够诱导更多富Al相生成,进而提升Zn合金的力学性能。此外SLM技术快速熔化和快速凝固的特点能够细化共晶组织,在凝固过程中Sn也能起到粘结作用,增加合金致密度,从而进一步增强Zn合金的力学性能,促进了其作为可降解植入物在组织修复领域的应用。(The invention relates to a needle-shaped eutectic reinforced biological Zn-Al-Sn alloy and a preparation method thereof. The biological Zn-Al-Sn alloy contains 90-92% of Zn, 7% of Al and 1-3% of Sn. The preparation method comprises the following steps: taking raw materials according to the designed components, and carrying out ball milling and mixing; then, an SLM technology is adopted to prepare the alloy. According to the invention, by utilizing the characteristic that Zn and Sn can form acicular eutectic, acicular eutectic structures which are randomly oriented and uniformly distributed are prepared, the bearing capacity of a matrix can be enhanced, and more Al-rich phases can be induced by Sn in the solidification process, so that the mechanical property of Zn alloy is improved. In addition, the characteristics of quick melting and quick solidification of the SLM technology can refine eutectic structures, Sn can also play a role in bonding in the solidification process, and the density of the alloy is increased, so that the mechanical property of the Zn alloy is further enhanced, and the application of the Zn alloy as a degradable implant in the field of tissue repair is promoted.)

1. A needle-like eutectic reinforced biological Zn-Al-Sn alloy; the method is characterized in that: the needle-shaped eutectic reinforced biological Zn-Al-Sn alloy contains 90-92 wt% of Zn, 7 wt% of Al and 1-3 wt% of Sn.

2. An acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 1; the method is characterized in that: the content of Sn in the needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy is 2-3 wt%.

3. The needle-like eutectic enhanced biological Zn-Al-Sn alloy of claim 1, wherein the needle-like eutectic enhanced biological Zn-Al-Sn alloy has a Sn content of 2 wt%.

4. A method of preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to any one of claims 1 to 3, characterized by; the method comprises the following steps:

step one

Distributing Zn powder, Al powder and Sn powder according to a design group, and ball-milling for 2-4h at ball-material mass ratio of 10:1-30:1 and ball-milling rotation speed of 250-400r/min under protective atmosphere to obtain Zn-Al-Sn mixed powder;

step two

Taking the Zn-Al-Sn mixed powder obtained in the step one as a raw material, and preparing a needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy by adopting an SLM (selective laser melting) process under a protective atmosphere; the laser power is controlled to be 80-90W, the scanning speed is 100-120mm/s, the spot diameter is 50 mu m, the laser scanning interval is 0.08-0.1mm, and the powder spreading thickness is 0.1-0.2 mm.

5. The method for preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 4, wherein: the ball-material mass ratio is 20:1-30:1, the ball-milling rotation speed is 350-.

6. The method for preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 4, wherein: the ball-material mass ratio is 20:1, the ball milling rotation speed is 400r/min, and the ball milling is carried out for 4 h.

7. The method for preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 4, wherein: the laser power is controlled to be 85-90W, the scanning speed is 100-110mm/s, the laser scanning interval is 0.08 mu m, and the powder spreading thickness is 0.1 mm.

8. The method for preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 4, wherein: the laser power was controlled to 90W and the scanning rate was 100 mm/s.

9. The method for preparing an acicular eutectic strengthened biological Zn-Al-Sn alloy according to claim 4, wherein: the protective atmosphere is high-purity argon with the purity of more than or equal to 99.999 percent.

Technical Field

The invention belongs to the technical field of design and preparation of biological materials, and particularly relates to a needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy and a preparation method thereof.

Background

The biodegradable metal has good biocompatibility and degradability, and has wide application prospect in orthopedic implant application. The research on biodegradable metals at present mainly focuses on three types of Zn, Mg and Fe, wherein Zn has a degradation rate more similar to the growth of human bone tissues, and is considered to be a bone repair material with great potential. On the one hand, Zn is able to promote the formation and growth of new bone, called "calcium in the 21 st century" by researchers; on the other hand, Zn is a very potent selective osteoclast resorption inhibitor, and can prevent osteoporosis. However, Zn has poor mechanical properties and it is difficult to meet the requirements of bone implants for strength. Therefore, how to improve the mechanical property of Zn is a problem which needs to be solved urgently at present.

The element alloying is an effective method for improving the mechanical property of Zn. For example, researchers have attempted to alloy Mg with Zn to improve mechanical properties, but it was found that the addition of Mg produces a hard and brittle second phase of Mg₂Zn₁₁Leading to a decrease in the toughness of the Zn alloy; in addition, some researchers have alloyed Cu and Fe as alloying elements into Zn, and hopefully formed an intermetallic compound FeZn having excellent mechanical properties₁₃、CuZn₅To improve the mechanical properties, it was found that although the strength of the alloy is improved, the intermetallic compound formed has sharp corners, so that cracks are easily formed at the sharp corners, deteriorating the mechanical properties of the alloy.

In addition, some researchers hope to control the morphology and size of the second phase by improving the preparation process, and hope to improve the strength of the Zn alloy and simultaneously reduce the influence of the morphology of the second phase on the toughness and the elongation of the alloy. For example, the Mn powder and the Zn powder are firstly ball-milled and then are prepared into the alloy by adopting a cold pressing and sintering preparation process, on one hand, the preparation process can achieve the purposes of changing the form of a second phase and improving the mechanical property of the alloy, but on the other hand, the powder is not completely melted in the forming process, so that the density of the alloy is reduced, and the improvement of the mechanical property of the Zn alloy is limited.

Therefore, how to effectively improve the mechanical properties such as strength and toughness of the biological Zn alloy is still an important direction for research on the biological Zn alloy as a degradable bone implant.

Disclosure of Invention

Aiming at the problem of insufficient mechanical properties of the existing biological Zn alloy, the invention provides a needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy and a preparation method thereof. The needle-shaped eutectic reinforced biological Zn-Al-Sn alloy consists of a Zn matrix, a Zn-Al eutectic and a Zn-Sn eutectic. On one hand, Sn and Zn can perform eutectic reaction to form an acicular eutectic structure; on the other hand, Sn plays a role of a binder in the Zn solidification process, so that the compactness of the alloy is improved; moreover, Sn can induce Al element to be precipitated, so that more Al-rich strengthening phases are generated in the matrix, and the mechanical property of the biological Zn alloy is improved under the combined action of the Sn, the Al and the strengthening phases.

The needle-shaped eutectic reinforced biological Zn-Al-Sn alloy contains 90-92 wt% of Zn, 7 wt% of Al and 1-3 wt% of Sn.

Preferably, the content of Sn in the acicular eutectic reinforced biological Zn-Al-Sn alloy is 2-3 wt%. More preferably, the content of Sn in the acicular eutectic reinforced biological Zn-Al-Sn alloy is 2 wt%.

The invention firstly tries to alloy Sn and Al into Zn by utilizing a Selective Laser Melting (SLM) process to prepare the needle-shaped eutectic reinforced biological Zn-Al-Sn alloy, which comprises the following steps:

step one

Distributing Zn powder, Al powder and Sn powder according to a design group, and ball-milling for 2-4h at ball-material mass ratio of 10:1-30:1 and ball-milling rotation speed of 250-400r/min under protective atmosphere to obtain Zn-Al-Sn mixed powder;

step two

Taking the Zn-Al-Sn mixed powder obtained in the step one as a raw material, and preparing a needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy by adopting an SLM (selective laser melting) process under a protective atmosphere; the laser power is controlled to be 80-90W, the scanning speed is 100-120mm/s, the spot diameter is 50 mu m, the laser scanning interval is 0.08-0.1mm, and the powder spreading thickness is 0.1-0.2 mm.

Preferably, in the first step of the invention; the granularity of Zn powder is 40-50 microns; the granularity of the Al powder is 5-10 microns; the particle size of the Sn powder is 1-5 microns.

Preferably, in the first step of the invention: the ball-material mass ratio is 20:1-30:1, the ball-milling rotation speed is 350-. More preferably: the ball-material mass ratio is 20:1, the ball milling rotation speed is 400r/min, and the ball milling is carried out for 4 h.

Preferably, in step two of the present invention: the laser power is controlled to be 85-90W, the scanning speed is 100-110mm/s, the laser scanning interval is 0.08 mu m, and the powder spreading thickness is 0.1 mm. More preferably: the laser power was controlled to 90W and the scanning rate was 100 mm/s.

Preferably, in step two of the present invention: the protective atmosphere is high-purity argon with the purity of more than or equal to 99.999 percent.

The needle-shaped eutectic-reinforced biological Zn-Al-Sn alloy designed and prepared by the invention has obvious advantages when being used as a degradable implant.

The needle-shaped eutectic reinforced biological Zn-Al-Sn alloy designed and prepared by the invention has the ultimate compressive strength of 280-330 MPa.

Principles and advantages

The invention firstly tries to alloy Al and Sn in the biological Zn alloy by utilizing the SLM process to prepare the needle-shaped eutectic reinforced biological Zn-Al-Sn alloy. (1) The characteristics of laser rapid melting and rapid solidification can rapidly alloy three kinds of metal powder, according to a Zn-Al-Sn ternary alloy phase diagram, Sn and Zn can generate eutectic reaction in the solidification process to form a needle-shaped eutectic structure, and a hard and brittle second phase cannot be formed, and the needle-shaped eutectic with random orientation distribution can improve the mechanical property of the alloy by blocking crack propagation. (2) The solidification temperature of Sn is lower than that of Zn and Al, so that the Sn can play a role of a binder in the solidification process of the alloy, the density of the alloy is improved, and the mechanical property of the Zn alloy is further improved. (3) Sn can induce Al element to be separated out, so that more Al-rich phases are generated in the matrix, and the mechanical property of the Al-rich phases is better than that of the matrix, so that the mechanical strengthening effect is further achieved.

According to the invention, by controlling the Sn content in the raw materials and matching with high-speed ball milling and special SLM (selective laser melting) process parameters, a large amount of needle-shaped eutectic phases can be formed in the alloy, and the formation of an Al-rich phase with excellent mechanical property is induced, so that necessary conditions are provided for improving the mechanical property of a matrix. When the Sn content is higher than the parameter range of the invention, a large amount of Sn-rich phases can be formed, and the mechanical property of the Zn alloy can be reduced due to the poor mechanical property of the Sn-rich phases; when the Sn content is lower than the parameter range of the invention, the acicular eutectic phase is difficult to form, and the function of improving the mechanical property of the Zn alloy can not be achieved.

According to the invention, three kinds of metal powder can be uniformly mixed by optimizing a ball milling process, so that the generated needle-shaped eutectic and the Al-rich phase can be uniformly distributed in the matrix. When the ball milling parameter is higher than the parameter range of the invention, the serious powder deformation and cold welding phenomena can be caused, the powder fluidity and the final laser forming quality are damaged, and the mechanical property of the Zn alloy is further deteriorated; when the ball milling parameter is lower than the parameter range of the invention, the powder is difficult to be uniformly dispersed and even has serious agglomeration phenomenon, which affects the distribution of the eutectic phase and the Al-rich phase in the alloy and the interface combination of the eutectic phase and the Al-rich phase and the matrix, and leads to the reduction of the mechanical property and the performance consistency of the alloy.

After the ball milling is finished, an SLM process in a specific range is used as an auxiliary process, the powder is rapidly melted, solidified and molded by utilizing the shock cooling and shock heating when the laser and the powder act, and SLM process parameters have important influence on the forming quality and mechanical property of the alloy. For example, when the laser power is higher than the parameter range of the invention, the laser can cause serious powder vaporization and splashing, and the forming quality is poor or even the forming is difficult; when the laser power is lower than the parameter range of the invention, the powder is difficult to be completely melted and bonded together, thereby not only generating defects such as gaps and the like to influence the compactness of the alloy, but also reducing the formation of eutectic phase and Al-rich phase to damage the mechanical property of the alloy.

In conclusion, Al and Sn with proper content are added into Zn, a needle-shaped eutectic phase and an Al-rich phase are formed in a Zn matrix through the optimization of Sn content, ball milling and SLM process parameters, and the compactness of the alloy is improved through the action of a binder, so that the mechanical property of the Zn alloy is enhanced. The developed Zn-Al-Sn alloy not only can obtain enhanced mechanical property, but also has excellent biocompatibility and degradation performance, and can be used for repairing human tissues.

Drawings

FIG. 1 is a microstructure morphology and an element distribution diagram of Zn-Al-Sn alloys prepared in example 1, comparative example 1 and comparative example 2;

FIG. 2 is a DSC curve and XRD pattern of Zn-Al-Sn alloy prepared in example 1;

FIG. 3 is a macro topography before and after compression test of the products obtained in example 1 and comparative example 4.

Detailed Description

The following examples illustrate specific embodiments of the present invention: