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PRODUCTION OF HIGH FRACTURE TOUGHNESS AND HIGH FATIGUE STRENGTH BULK METALLIC GLASSES AND EXAMINATION OF THE MECHANISM

高断裂韧性和高疲劳强度大块金属玻璃的制备及机理检验

基本信息

批准号：
14350063
负责人：
FUJITA Kazutaka
金额：
$ 8.96万
依托单位：
Ube National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Single phase (SF) bulk glassy alloys (BGAs) and nanocrystalline (NC) EGAs of some Zr-, Cu- and Pd-based systems have been synthesized by some fabrication methods. Where, the NC BGA is the glassy alloy which contain nano-scale crystalline particles embedded homogeneously in glassy matrix. Then fatigue strength and fracture toughness in these BGAs were examined.The ratio of fatigue limit (σ_w ; half a full stress amplitude) under stress ratio of 0.1 to tensile strength (σ_B) of the Zr-based NC BGA showed a value of 15% (σ_B=1.7 GPa), and it was approximately three times larger compared with the ratio of the SF BGA of the same composition. The ratio of σ_w to σ_B of the Cu-based BGA exhibited a very large value of 24% (σ_B=2.0 GPa). These σ_w s show the enough values for applications. It is thought that the drastic rise in the σ_w of these NC BGAs is derived from the prevention of slip initiation and propagation by the NC particles.A Zr-based BGA with a high degree of amorphousness exhibited a fracture touness value (Kic) of 53 MPa・m^<1/2>. It was clarified that the Zr-based BGA has a sufficient Kic for practical uses. The Kic s of a Zr-based NC BGA and considerably crystallized Zr-based BGA were small even in the maximum value with 40 and 11 MPa・m^<1/2>, respectively. This is thought to be due to the embrittlement by the crystallization.The Pd-based SF BGA could not have fatigue cracks, and the value of notched fracture toughness exhibit 36 MPa・m^<1/2> and cracks propagated in three or more directions at the same time. An estimated K/c showed a small value of 12 MPa・m^<1/2>.

采用多种方法合成了Zr基、Cu基和Pd基单相大块非晶合金和纳米晶EGA。其中，NC BGA是在玻璃态基体中均匀嵌入纳米晶颗粒的玻璃态合金。在应力比为0.1时，Zr基NC BGA的疲劳极限（σ w ;半个全应力幅）与抗拉强度（σ B）之比为15%（σ B=1.7 GPa），约为相同成分SF BGA的3倍。Cu基BGA的σ_w与σ_B之比为24%（σ_B=2.0 GPa）。这些σ_w s为应用提供了足够的数值。结果表明，这些非晶球栅阵列的σ_w急剧上升是由于NC颗粒阻止了滑移的产生和扩展，具有高度非晶化的Zr基球栅阵列的断裂韧性值（Kic）为53 MPa. m^<1/2>。澄清了Zr基BGA具有足够的Kic用于实际用途。Zr基NC BGA和相当结晶化的Zr基BGA的Kic s即使在最大值处也很小，分别为40和11 MPa·m^<1/2>。Pd基SF BGA不会产生疲劳裂纹，缺口断裂韧性值为36 MPa·m^<1/2>，裂纹同时向三个以上方向扩展。估算的K/c值很小，为1/2 MPa·m^<1/2>。