Effect of phase change from nonequilibrium to equilibrium phase on densification process and formation of nanocrystallin material

从非平衡相到平衡相的相变对纳米晶材料致密化过程和形成的影响

• 批准号: 11650738
• 负责人: ISONISHI Kazuo
• 金额: $ 2.37万
• 依托单位: Shiga University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650738/
• 关键词: densification process; pressure sintering; vacuum hot pressing; titanium silicide; Ti_5Si_3; mechanical alloying; phase change from nonequilibrium phase; hardness test; 超塑性変形; MA; 非平衡相; MA粉末; Ti_5Si_3; 金属間化合物

In this investigation, densification behavior of alloyed powder having non-equilibrium phase was discussed. Especially, effect of phase change from nonequilibrium phase to equilibrium phase on densification process of pressure sintering. The alloy composition of powder used here was Ti-37.5 mol %Si, that was obtained by using mechanical alloying technique. Long time milling more than 540 ks made the mixture of the powder amorphous state. 3600 ks milled amorphous powder was used. In addition to the amorphous powder, lamellar structure (Ti + Si) powder milled for 360 ks was also used as to compare the densification behavior of amorphous powder.At first, phase formation characteristics of amorphous and lamellar powder were discussed. Based on the evidence of phase change to stable intermetallic compounds, densification behavior of MAed powder was investigated using vacuum hot pressing (VHP) method. Before heating of VHP, hot pressing pressure (10-200MPa) was applied. With keeping the pres … More sure constant, pressed powder was heated at the rate of 5-20 K/min up to 1273 K, then kept for 10.8 ks. MA powders consisting amorphous phase and (Ti + Si) lamellar structure showed extraordinary densification during phase formation period that was measured by DTA analysis. The following effects were examined to make clear the densification behavior. Those are (1) Exothermic heating during phase formation, (2) Powder re-arrangement, (3) Thermal expansion of compacts having nonequilibrium phases, (4) Pressure and heating rate dependence on densification. It is concluded that the enhanced densification during phase formation period was due to the enhanced deformation of powder particle.After the phase change from nonequilibrium to stable phase, in the case of amorphous powder, densification ceased foray little while due to the formation of Ti_5Si_3 intermetallic compound up to 1050 K. On the other hand, lamellar powder having reduced Ti phase kept to increase density. When the temperature reached 1050K, densification restarted again. It is thought that the densification progressed at these higher temperature over 1050 K by the mechanism of grain boundary sliding (fine microstructure superplasticity) due to the nano size microstructure about 100 nm.The VHP compact made from amorphous powder showed nano size microstructure expressed hardness of HV1336 and fracture toughness K_<Ic> = 1.84MPa・m^<0.5>. Less

研究了非平衡相合金粉末的致密化行为。重点研究了非平衡相到平衡相的相变对压力烧结致密化过程的影响。本文所用粉末的合金成分为Ti-37.5 mol %Si，采用机械合金化技术获得。长时间铣削540ks以上使混合物粉末呈非晶态。采用3600ks磨晶非晶粉末。除了非晶粉末外，还采用层状结构（Ti + Si）粉末进行了360 k的研磨，比较了非晶粉末的致密化行为。首先讨论了非晶和层状粉末的相形成特性。基于相变为稳定的金属间化合物的证据，采用真空热压（VHP）方法研究了MAed粉末的致密化行为。在VHP加热前，施加10-200MPa的热压压力。在保持压机恒定的情况下，以5- 20k /min的速度加热，直至1273 K，保存10.8 ks。DTA分析表明，由非晶相和（Ti + Si）层状结构组成的MA粉末在相形成过程中致密化程度显著。为了明确致密化行为，研究了以下效应。它们是(1)相形成过程中的放热加热，(2)粉末重排，(3)具有非平衡相的压块的热膨胀，(4)压力和加热速率对致密化的依赖。结果表明，相形成过程中致密化的增强是由于粉末颗粒变形的增强。非晶态粉末由非平衡相转变为稳定相后，在1050 K时，由于Ti_5Si_3金属间化合物的形成，致密化过程短暂停止。另一方面，钛相还原后的层状粉末密度继续增大。当温度达到1050K时，重新开始致密化。在1050 K以上的高温下，合金的致密化过程是通过晶界滑动机制（微细组织超塑性）进行的。由非晶粉末制成的VHP致密体具有纳米级微观结构，硬度为HV1336，断裂韧性K_<Ic> = 1.84MPa·m^<0.5>。少

项目成果

Kazuo ISONISHI: "Densification Behavior of Mechanically Alloyed Powders Having. Unstable Phases by Vacuum Hot Pressing"Proc. 2000 Powder Metallurgy World Congress. 3. 1705-1708 (2000)

Kazuo ISONISHI：“通过真空热压具有不稳定相的机械合金粉末的致密化行为”Proc。

Kazuo ISONISHI: "Densification Behavior of Mechanically Alloyed Powders Having Unstable Phases by Vacuum Hot Pressing"Proc.2000 Powder Metallurgy World Congress. 3. 1705-1708 (2000)

Kazuo ISONISHI：“真空热压具有不稳定相的机械合金粉末的致密化行为”Proc.2000 粉末冶金世界大会。

Kazuo ISONISHI: "Densification Behavior of Mechanically Alloyed Powders Having Unstable Phases by Vacuum Hot Pressing."Proc.PM2000 world comgress. (in press). (2001)

Kazuo ISONISHI：“通过真空热压具有不稳定相的机械合金粉末的致密化行为。”Proc.PM2000 世界大会。

磯西 和夫, 浅野 正浩: "非平行相からなるMA粉末の加圧焼結における相変化の効果"粉体および粉末冶金. 48. 77-81 (2001)

Kazuo Isonishi、Masahiro Asano：“由非平行相组成的 MA 粉末压力烧结中的相变效应”《粉末与粉末冶金》48. 77-81 (2001)。

Kazuo ISONISHI, Masahiro Asano: "Effect of Phase Change on Densification Process of MA powder Having Unsteblre Phase by Pressure Sintering"J. Japan Society of Powder and Powder Metallurgy. 48-1. 77-81 (2001)

Kazuo ISONISHI，Masahiro Asano：“相变对加压烧结具有不稳定相的MA粉末致密化过程的影响”J。