本文選題：TiAl合金 + WC�。� 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：TiAl合金具有很多優(yōu)異的綜合性能,在航空航天有著廣泛的應(yīng)用。隨著航空航天發(fā)動(dòng)機(jī)向著更快更強(qiáng)的目標(biāo)發(fā)展,TiAl合金作為結(jié)構(gòu)材料的力學(xué)性能還需進(jìn)一步提高。改善和提高TiAl合金性能的有效方法是合金化,或者是通過(guò)原位自生的方法生成增強(qiáng)相來(lái)提高合金的綜合力學(xué)性能。本文采用真空電弧熔煉的方法在TiAl二元合金中加入WC和SiC,研究添加不同質(zhì)量分?jǐn)?shù)的WC和SiC對(duì)Ti43Al和Ti47Al二元合金的影響,通過(guò)OM、SEM、EPMA、XRD等方法觀察和測(cè)試顯微組織結(jié)構(gòu),并對(duì)其室溫壓縮性能進(jìn)行了測(cè)試,研究在不同WC和SiC添加量下合金力學(xué)性能的變化規(guī)律,分析討論WC和SiC對(duì)TiAl二元合金的作用機(jī)理和強(qiáng)化機(jī)制。實(shí)驗(yàn)結(jié)果表明,在Ti43Al中加入WC后,Ti43Al合金的顯微組織得到細(xì)化,室溫壓縮強(qiáng)度和壓縮率都得到一定的提升。當(dāng)WC添加量為4.5wt%時(shí),合金顯微組織一次枝晶臂間距達(dá)到最小為70.65μm,壓縮強(qiáng)度為1235.11MPa,與Ti43Al基體合金相比提高了46.62%。當(dāng)WC添加量達(dá)到6.0wt%和7.5wt%時(shí),基體片層組織中出現(xiàn)細(xì)長(zhǎng)針狀增強(qiáng)相,XRD分析表明增強(qiáng)相是Ti2AlC,且其室溫壓縮性能和壓縮率逐漸下降。WC對(duì)Ti47Al的組織和性能也有一定影響,隨著WC加入量的不斷增加,基體片層中出現(xiàn)棒狀增強(qiáng)相,且其數(shù)量逐漸增多,分布均勻,XRD分析表明基體中生成了Ti2AlC增強(qiáng)相,α2相的最強(qiáng)衍射峰向左偏移,Ti47Al-xWC合金的顯微組織明顯細(xì)化,由最初的柱狀枝晶轉(zhuǎn)變成四重對(duì)稱(chēng)等軸晶組織,晶粒尺寸由原始的141.86μm減小到60.02μm,室溫壓縮強(qiáng)度和壓縮率都逐漸提升。當(dāng)WC添加量為6.0wt%時(shí),晶粒尺寸達(dá)到最小為60.02μm,室溫壓縮強(qiáng)度達(dá)到最大為2323.99MPa,與Ti47Al基體合金相比提高了21.19%。在Ti43Al中加入SiC后,當(dāng)SiC添加量為0.1、0.3、0.5、0.7wt%時(shí),Ti43Al-xSiC的組織和室溫壓縮性能變化不明顯,但是當(dāng)SiC的加入量達(dá)到0.9wt%時(shí),晶粒尺寸為105.99μm,Ti43Al合金的顯微組織由粗大的柱狀晶組織變成細(xì)小的等軸晶組織。室溫壓縮強(qiáng)度大幅度提升,壓縮強(qiáng)度達(dá)到1382.72MPa,與Ti43Al基體合金相比提高了64.14%。SiC對(duì)Ti47Al合金的組織和性能有顯著的影響,當(dāng)在Ti47Al中加入SiC后,隨著SiC加入量的增多,基體片層中生成了細(xì)小棒狀的Ti2AlC增強(qiáng)相,晶界處彌散分布大量的富Si析出相。當(dāng)SiC添加量為0.5wt%時(shí),壓縮強(qiáng)度達(dá)到最大值為2196.49MPa,與基體合金相比提高了19.94%。
[Abstract]:Tial alloys have many excellent comprehensive properties and are widely used in aeronautics and astronautics. The mechanical properties of tial alloys as structural materials need to be further improved with the development of aerospace engines towards faster and stronger targets. The effective way to improve and improve the properties of tial alloys is to improve the comprehensive mechanical properties of tial alloys by alloying or by in-situ generation of reinforcing phases. In this paper, WC and sic were added to tial binary alloy by vacuum arc melting. The effect of WC and sic on Ti43Al and Ti47Al binary alloy was studied. The microstructure was observed and tested by OMSEMEPMA-XRD. The compressive properties at room temperature were tested and the mechanical properties of the alloys with different WC and sic contents were studied. The mechanism and strengthening mechanism of WC and sic on tial binary alloys were analyzed and discussed. The experimental results show that the microstructure of Ti43Al alloy is refined and the compression strength and compression ratio of Ti43Al alloy are improved at room temperature after adding WC into Ti43Al alloy. When the WC content is 4.5 wt%, the primary dendritic arm spacing of the alloy microstructure reaches the minimum of 70.65 渭 m and the compression strength is 1235.11 MPA, which is 46.62% higher than that of Ti43Al matrix alloy. When WC content reached 6.0 wt% and 7.5 wt%, XRD analysis showed that the reinforcing phase was Ti _ 2AlC, and the compression properties and compressibility of Ti _ (47) Al decreased gradually at room temperature. The microstructure and properties of Ti _ (47) Al were also affected by WC. With the increasing of WC content, the rod-like reinforcement phase appears in the matrix layer, and its number increases gradually. XRD analysis showed that Ti _ 2AlC reinforcement phase was formed in the matrix, and the microstructure of Ti _ 47 Al-xWC alloy with the strongest diffraction peak shifted to the left of 偽 _ 2 phase was obviously refined, which changed from columnar dendrite to four-fold symmetrical equiaxed structure, and the microstructure of Ti _ (47) Al-xWC alloy was changed from columnar dendrite to tetra-symmetric equiaxed structure. The grain size was reduced from 141.86 渭 m to 60.02 渭 m, and the compression strength and compression ratio increased gradually at room temperature. When WC content is 6.0 wt%, the grain size reaches the minimum of 60.02 渭 m and the maximum compression strength at room temperature is 2323.99 MPA, which is 21.19% higher than that of Ti47Al matrix alloy. When sic was added into Ti43Al, the microstructure and room temperature compressive properties of Ti43Al-xSiC did not change obviously when the amount of sic was 0.1wt% 0.3U 0.5wt%, but when the content of sic reached 0.9wt%, the microstructure and room temperature compressive properties of Ti43Al-xSiC did not change obviously. The microstructure of Ti43Al alloy with grain size of 105.99 渭 m is changed from coarse columnar structure to fine equiaxed structure. The compression strength of Ti47Al alloy was increased greatly at room temperature, and the compressive strength reached 1382.72 MPa. Compared with Ti43Al matrix alloy, the microstructure and properties of Ti47Al alloy were significantly increased by 64.14.SiC. When sic was added into Ti47Al, the content of sic increased with the increase of sic content. A fine rod reinforced Ti _ 2AlC phase was formed in the matrix, and a large number of Si-rich precipitates were dispersed at the grain boundaries. When the content of sic was 0.5 wt%, the compressive strength reached the maximum value of 2196.49 MPa, which increased 19.94% compared with the matrix alloy.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG146.23
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本文編號(hào)：2077105