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>.

一些Zr、Cu和Pd基体系的单相（SF）块状非晶合金（BGA）和纳米晶（NC）EGA已经通过一些制造方法合成，其中NC BGA是含有纳米-的非晶合金。鳞片晶粒均匀地嵌入玻璃基体中，然后检查了这些 BGA 的疲劳强度和断裂韧性。在应力比为Zr基NC BGA的0.1与抗拉强度(σ_B)的值为15%(σ_B=1.7 GPa)，与相同成分的SF BGA相比，该值大约大三倍。 Cu 基 BGA 的 σ_w 表现出非常大的值 24% (σ_B=2.0 GPa)。人们认为，这些 NC BGA 的 σ_w 急剧上升是由于 NC 颗粒阻止了滑移引发和传播。具有高度非晶性的 Zr 基 BGA 的断裂弹性值 (Kic) 为 53 MPa·m^<1/2> 可知Zr系BGA具有足够实用的Kic，与Zr系NC BGA的Kic s相当。结晶化的Zr基BGA即使在最大值时也很小，分别为40和11MPa·m^<1/2>，这被认为是由于结晶导致的脆化。Pd基SF BGA不能具有。疲劳裂纹，缺口断裂韧性值为36MPa·m^<1/2>，裂纹同时向3个以上方向扩展，推定K/c显示较小。值为12MPa·m^<1/2>。