Refining Mechanism of 7075 Al Alloy by In-Situ TiB₂ Particles.
Refining Mechanism of 7075 Al Alloy by In-Situ TiB₂ Particles.
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TiB2颗粒原位细化7075铝合金的机理
DOI：
10.3390/ma10020132
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发表时间：
2017-02-04
期刊：
影响因子：
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通讯作者：
Wu Y
中科院分区：
文献类型：
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作者：
Gan G;Yang B;Zhang B;Jiang X;Shi Y;Wu Y
研究了TiB 2/7075铝基复合材料的形核过冷度、不同冷却速率下凝固后的显微组织以及TiB 2颗粒的尺寸和分布。结果表明，随着TiB 2含量的增加，TiB 2/7075铝基复合材料的晶粒尺寸先减小后增大，最后又减小。当冷却速率分别为5 ° C/min和10 °C/min时，随着TiB 2含量的增加，TiB 2/7075 Al基复合材料的形核过冷度先增大后减小，最后又增大，在冷却速率为20 °C/min时，随着TiB 2含量的增加，合金的熔化和凝固过程基本不随冷却速率的降低而变化TiB 2/7075 Al基复合材料大多数小颗粒可以作为异质核，诱导晶粒生长并被固/液界面捕获到晶粒中。同时，大部分较大的颗粒和少数较小的TiB 2颗粒被推入晶界，位于晶界可以阻碍Al原子在凝固过程中的扩散，抑制α-Al相的生长。随着TiB 2颗粒数量的增加，颗粒的影响从定位为主转变为形核为主。
The nucleation undercooling of TiB2/7075 Al matrix composites, the microstructure observed after solidification at different cooling rate, and the size and distribution of TiB2 particles were investigated. The experimental results have shown that the grain sizes of TiB2/7075 Al matrix composites firstly decreased, then increased, and finally decreased again with the increase of TiB2 content. The nucleation undercooling of TiB2/7075 Al matrix composites first increased, then decreased, and finally increased again with the increase of TiB2 content when the cooling rates was 5 and 10 °C/min respectively, but kept decreasing with the increase of TiB2 content at a cooling rate of 20 °C/min. The melting and solidification process showed no significant change with the decrease of cooling rate in 9.0% TiB2/7075 Al matrix composites. Most small particles can act as heterogeneous nucleus, which induced grain growth and were captured into the grain by the solid/liquid interface. At the same time, most of the larger particles and a minority of the small TiB2 particles are pushed into the grain boundary; locating in the grain boundary can hinder the Al atoms from diffusing during the solidification process and restrain α-Al phase growth. The influence of particles shifted from dominating by locating to dominating by nucleation as the quantity of TiB2 particles increased.