Microstructural coarsening of 7005 aluminum alloy semisolid billets with high solid fraction
Microstructural coarsening of 7005 aluminum alloy semisolid billets with high solid fraction
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高固相7005铝合金半固态坯料显微组织粗化
DOI：
10.1016/j.matchar.2014.01.017
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发表时间：
2014-04
影响因子：
4.7
通讯作者：
Atkinson H. V.
中科院分区：
文献类型：
--
作者：
Jiang Jufu;Wang Ying;Atkinson H. V.
在本研究中，7005铝合金坯料在温挤压和T6热处理状态下供应。然后，他们被重新加热到半固态和微观组织的演变和粗化的调查。如果坯料要通过半固态加工成型，这是必要的基础，半固态加工是一种创新的制造路线，最近已广泛用于各种铝合金，但尚未应用于7005。结果表明，随着保温时间的延长，7005铝合金的平均球状体尺寸、液膜厚度和液相率均增大。晶内液滴存在于固体颗粒中，并随保温时间和等温温度的增加而粗化。在620 °C下浸泡长达12分钟的时间后，在600 °C-615 °C下处于半固体状态的固体小球的圆度在1.5至2.0的范围内，但对于大于15分钟的时间，圆度大于2，这不太可能适用于半固体成形工艺，其中需要平滑流动并因此需要相对圆的小球。当等温温度为600 °C、610 °C、615 °C和620 °C时，粗化速率分别为542 μ m3 s-1、606 μ m3 s-1、683 μ m3 s-1和688 μ m3 s-1。粗化速率K随等温温度的升高而增大。这些值将该合金置于正常铸造合金的典型粗化速率和正常锻造合金的典型粗化速率之间的分界线上。这归因于这样的事实，即与其它7 xxx合金相比，该合金具有相对简单的沉淀硬化系统，并且硬化沉淀物（MgZn 2）在低于进行实验的温度下熔化，因此防止了抑制液膜迁移的沉淀物和在球体边界处沿着窄液膜的扩散。粗化倾向于通过Ostwald熟化和合并发生，但随着等温温度的升高，Ostwald熟化的作用越来越大。
In the present study, 7005 aluminum alloy billets were supplied in the warm extruded and T6 heat treated state. They were then reheated to the semisolid state and the microstructural evolution and coarsening investigated. This is necessary groundwork if the billets are to be formed to shape by semisolid processing, an innovative manufacturing route which has recently gained wide use for a range of aluminum alloys but which has not yet been applied to 7005. The results showed that the average spheroid size, liquid film thickness and liquid fraction of 7005 aluminum alloy increased with increase in soaking time. Intragranular liquid droplets were present in solid grains, and coarsened with increase in soaking time and isothermal temperature. The roundness of globules of solid in the semisolid state at 600 °C–615 °C was in the range of 1.5 to 2.0 after soaking for periods up to 12 min at 620 °C, but for times greater than 15 min was more than 2, which is unlikely to be suitable for the semi-solid forming process, where smooth flow is required and therefore relatively round globules. When the isothermal temperatures were 600 °C, 610 °C, 615 °C and 620 °C, the coarsening rates were 542 μm3s− 1, 606 μm3s− 1, 683 μm3s− 1and 688 μm3s− 1, respectively. The coarsening rateKincreased with the increase of isothermal temperature. These values place this alloy on the dividing line between typical coarsening rates for normally cast alloys and typical coarsening rates for normally wrought alloys. This is attributed to the fact that the alloy has a relatively simple precipitation hardening system in comparison with other 7xxx alloys and the hardening precipitate (MgZn2) melts below the temperature the experiments have been carried out at, hence preventing the precipitates inhibiting liquid film migration and diffusion along narrow liquid films at spheroid boundaries. Coarsening tends to occur via Ostwald ripening and coalescence, but Ostwald ripening plays an increasing role with the increase of isothermal temperature.
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影响因子：
6.3
作者：
De-hong Lu;Ye-hua Jiang;Guisheng Guan;R. Zhou;Zhenhua Li;R. Zhou
通讯作者：
De-hong Lu;Ye-hua Jiang;Guisheng Guan;R. Zhou;Zhenhua Li;R. Zhou
影响因子：
2.4
作者：
Atkinson, H. V.;Burke, K.;Vaneetveld, G.
通讯作者：
Vaneetveld, G.
DOI：
10.1016/j.msea.2004.05.004
发表时间：
2005-01-15
影响因子：
6.4
作者：
Chayong, S;Atkinson, HV;Kapranos, P
通讯作者：
Kapranos, P
DOI：
10.1016/s0921-5093(99)00226-9
发表时间：
1999-11-01
影响因子：
6.4
作者：
Ferrante, M;de Freitas, E
通讯作者：
de Freitas, E
影响因子：
4.5
作者：
Heesool Kim;I. Stone;B. Cantor
通讯作者：
Heesool Kim;I. Stone;B. Cantor