本文關(guān)鍵詞： 噴射沉積鎂合金 (Ca Nd)Al2 熱壓縮 LPSO 織構(gòu)　出處：《內(nèi)蒙古科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：鎂合金是工程應(yīng)用中最輕的結(jié)構(gòu)金屬，具有比強度高以及減震性好等優(yōu)勢，，成為航空航天、汽車、軍工等領(lǐng)域?qū)崿F(xiàn)輕量化和節(jié)能減排的理想材料。與傳統(tǒng)鑄造鎂合金相比，噴射沉積技術(shù)制備的鎂合金晶粒細小、熱穩(wěn)定性高、合金化程度高、綜合力學(xué)性能優(yōu)良。但是鎂合金為HCP結(jié)構(gòu)，塑性成形能力差，在變形過程中容易形成強烈的(0002)基面織構(gòu)，嚴重限制了其應(yīng)用。 已有研究表明，稀土元素Nd和合金元素Ca的添加可以有效降低變形時基面織構(gòu)的強度，關(guān)于在Ca/Nd復(fù)合添加高合金化條件下，噴射沉積鎂合金熱變形過程組織及織構(gòu)演變規(guī)律研究目前較少。本文以噴射沉積鎂合金擠壓坯Mg-9Al-3Zn-6Ca-1Mn-1Nd為研究對象，在不同工藝條件下對其進行單道次熱壓縮變形，重點研究單道次熱壓縮變形過程中合金組織、織構(gòu)的演變規(guī)律，以及變形工藝對合金熱壓縮微觀組織及織構(gòu)的影響。主要研究結(jié)果如下： （1）噴射沉積鎂合金擠壓坯晶粒尺寸在3μm左右，基體中分布著大量尺寸300nm左右的“含Nd的Al2Ca相”((Ca,Nd)Al2)。合金中的層片狀組織為Mg-Nd-Zn系24R型LPSO結(jié)構(gòu)，擠壓坯中已經(jīng)形成了很強的(0002)基面織構(gòu)。 （2）在變形溫度250℃、應(yīng)變速率1s-1條件下，對噴射沉積鎂合金擠壓坯進行單道次熱壓縮變形，隨變形程度(ε=0.1、0.3、0.6)的增加合金柱面和錐面織構(gòu)逐漸增強、而基面織構(gòu)強度顯著降低，當(dāng)變形程度為0.6時，合金內(nèi)形成了基面、柱面和錐面共存的“復(fù)合織構(gòu)”類型。 （3）不同溫度(250℃、300℃、350℃)、應(yīng)變速率(0.01s-1、0.1s-1、1s-1)條件下對擠壓坯進行變形程度0.6的熱壓縮變形，隨溫度(250℃、300℃、350℃)的升高、應(yīng)變速率(0.01s-1、0.1s-1、1s-1)的增加，合金織構(gòu)的“隨機化”程度增加，并且在變形溫度350℃、應(yīng)變速率1s-1的條件下合金形變織構(gòu)的“隨機化”程度達到最高。
[Abstract]:Magnesium alloy is the lightest structural metal in engineering application. It has the advantages of high specific strength and good shock absorption. Magnesium alloy has become aerospace and automobile. Compared with the traditional casting magnesium alloy, the magnesium alloy prepared by spray deposition technology has fine grain, high thermal stability and high alloying degree. The comprehensive mechanical properties of magnesium alloy are excellent, but magnesium alloy is of HCP structure, and its plastic forming ability is poor, so it is easy to form strong texture of base plane in the process of deformation, which seriously limits its application. It has been shown that the addition of rare earth element ND and alloy element Ca can effectively reduce the strength of basic surface texture during deformation. There are few studies on the microstructure and texture evolution of spray deposited magnesium alloy during hot deformation. In this paper, Mg-9Al-3Zn-6Ca-1Mn-1Nd of extruded magnesium alloy is taken as the research object. Single pass thermal compression deformation was carried out under different technological conditions, and the evolution of microstructure and texture during single pass hot compression deformation was studied. And the effect of deformation process on the microstructure and texture of the alloy under hot compression. The main results are as follows: 1) the grain size of extruded magnesium alloy is about 3 渭 m, and a large amount of Al2Ca phase containing ND is distributed in the matrix. The lamellar structure of the alloy is Mg-Nd-Zn 24R type LPSO structure, and a strong basic texture has been formed in the extruded billet. (2) under the condition of deformation temperature 250 鈩

本文編號：1461651