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标题: 求解！新36套阅读EX16的一题 [打印本页]

作者: 許臨風_Zephyr 时间: 2014-9-5 23:14:18 标题: 求解！新36套阅读EX16的一题

原文如下：

When a molten metal or metallic alloy is cooled to a solid, a crystalline structure is formed that depends on the particular alloy composition. In contrast, molten nonmetallic glass-forming materials, when cooled, do not
assume a crystalline structure, but instead retain a structure somewhat like that of the liquid--an amorphous structure. At room temperature, the natural long-term tendency for both types of materials is to assume the crystalline structure. The difference between the two is in the kinetics or rate of formation of the crystalline structure, which is controlled by factors such as the nature of the chemical bonding and the ease with which atoms move relative to each other. Thus, in metals, the kinetics favors rapid formation of a crystal line structure, whereas in nonmetallic glasses the rate of formation is so slow that almost any cooling rate is sufficient to result in an amorphous structure.

12. It can be inferred from the passage that, theoretically, molten nonmetallic glasses assume a crystalline structure rather than an amorphous structure only if they are cooled
(A) very evenly, regardless of the rate
(B) rapidly, followed by gentle heating
(C) extremely slowly
(D) to room temperature
(E) to extremely low temperatures

这道题做错两次了，求大神详解。新36套给的答案是C。

作者: Electron_Volt 时间: 2014-9-5 23:27:29

重点就是理解这句：whereas in nonmetallic glasses the rate of formation is so slow that almost any cooling rate is sufficient to result in an amorphous structure.
因为它formation is so slo，所以不管cooling rate多慢，这个慢速度也足够让它形成amorphous structure.
所以理论上，cooling rate is extremely slow的时候是可以形成amorphous structure的

作者: 許臨風_Zephyr 时间: 2014-9-5 23:32:49

Electron_Volt 发表于 2014-9-5 23:27
重点就是理解这句：whereas in nonmetallic glasses the rate of formation is so slow that almost any co ...

可是题目问的是molten nonmetallic glasses assume a crystalline structure rather than an amorphous structure，最终目的是要变成crystalline structure啊= =

作者: Electron_Volt 时间: 2014-9-5 23:33:44

只是理论上，事实上无论速度多低都不会形成

作者: Electron_Volt 时间: 2014-9-5 23:38:40

許臨風_Zephyr 发表于 2014-9-5 23:32
可是题目问的是molten nonmetallic glasses assume a crystalline structure rather than an amorphous s ...

文章为什么会提到any cooling rate is sufficient to result in an amorphous structure，就是因为理论上extremely slow的时候它应该是可以形成n amorphous structure的。但是the rate of formation is so slow TOO。。所以事实上并不可以。。。
好难解释额= =

作者: hot13399 时间: 2015-10-4 14:29:36

許臨風_Zephyr 发表于 2014-9-5 23:32
可是题目问的是molten nonmetallic glasses assume a crystalline structure rather than an amorphous s ...

请问现在搞懂了没，我还是想不通。

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