Fatigue Strength and Fracture Mechanisms in Intermetllic Compound Particlate-Reinforced

金属间化合物颗粒增强材料的疲劳强度和断裂机制

基本信息

批准号：
06650081
负责人：
KATAGIRI Kazumune
金额：
$ 1.22万
依托单位：
IWATE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650081/
关键词：
Fatigue Strength Fatigue Crack Propagation Variable Stressing Elevated Temperature Metal Matrix Composites Die Casting NiAl Particle Ni_3Al Particle アルミニウム合金体積分率空洞析出物

项目摘要

Through the evaluation on static mechanical properties and fatigue characteristics as well as the microscopiic observations, it has been revealed that the intermetalic compund, NiAl and Ni_3Al, particle-reinforced Al die cast are superior to the SiC reinforced one as is shown in the followings.1. The endurance limit increases by reinforcement at room temperature. While the endurance limit ofmatrix die cast and SiC particle reinforced one decrease with temperature rise, reinforcement is effective at 200ﾟC in the NiAl and up to 300ﾟC in Ni_3Al particle. The endurance limit and fatigue life-time increase with increase in the particle volume fraction in all temperature ranges examined. Although these characteristics basically corresponds to that of 0.2% proof stress, suppression of local slip by the intermetalic compound particles together with precipitates such as Al_3Ni significantly contribute the fatigue strength at low stress.2. Fatigue crack initiates at voids located near the surfac … More e which are introduced on casting in all die casts. Crack propagates through the matrix and along the particle-matrix interface, and the former is dominant at elevated temperatures. No cracking in Ni_3Al particle is found.3. Fatigue crack propagation resistance of 2.5 vol% NiAl particle reinforced die cast is higher at near threshold region than the matrix and SiC reinforced one. It decreases when the particle volumefraction increase beyond 2.5%. In the crack propagation rate range of Paris rule or beyond it, 2.5 vol% NiAl particle reinforced die cast has higher crack propagation resistance while SiC has such low resistance as that in the matrix : These characteristics dose not coinside with that of fracture toughness.4. NiAl particle reinforce die cast has excellent fatigue characteristics against the two stage (low-high and high low) varying stress fatigue. Acceleration of fatigue crack propagation under intermittent oversrtressing and its microscopic mechanism in the intermetalic compound particle reinforced die cast is open problem. Less

通过静态力学性能和疲劳特性的评估以及显微观察，表明金属间化合物、NiAl和Ni_3Al、颗粒增强Al压铸件优于SiC增强压铸件，如下所示。 1. 室温下的耐久性极限通过强化而提高，而基体压铸件和 SiC 颗粒强化的耐久性极限则随着温度的升高而降低，而 NiAl 及以上的强化在 200°C 时有效。在所有温度范围内，Ni_3Al 颗粒的耐久性极限和疲劳寿命随着颗粒体积分数的增加而增加，尽管这些特性基本上与 0.2% 屈服强度的特性相对应，但金属间化合物对局部滑移的抑制。化合物颗粒与 Al_3Ni 等沉淀物一起显着提高了低应力下的疲劳强度。疲劳裂纹在靠近表面的空隙处萌生，这是在所有模具中铸造时引入的。裂纹沿基体和颗粒-基体界面扩展，且在高温下Ni_3Al颗粒中未发现裂纹。3．当颗粒体积分数增加超过 2.5% 或超过巴黎规则 2.5 时，在阈值区域附近，它会比基体和 SiC 增强材料降低。 vol% NiAl颗粒增强压铸件具有较高的裂纹扩展阻力，而SiC具有与基体一样低的阻力：这些特性与断裂韧性不相符。4．NiAl颗粒增强压铸件具有优异的两阶段疲劳特性。（低-高和高低）金属间化合物颗粒增强压铸件中疲劳裂纹扩展的加速及其微观机制是一个悬而未决的问题。