β相穩定元素與熱處理製程對α＋β鈦合金機械性質與顯微組織之影響

Effects of β Stabilizers and Heat Treatment on the Mechanical Properties and Microstructure of α + β Titanium Alloys

陳柏源(Bor-Yuan Chen)

指導教授 ： 黃坤祥

國立臺灣大學/工學院/材料科學與工程學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.00676

摘要

鈦和鈦合金具有密度低、比強度高、耐蝕性好、生物相容性佳以及高溫機械性質優良等特性，而利用粉末冶金製程可以製造幾何形狀複雜、組織結構均勻、高性能之淨形工件，因此利用粉末冶金製程製作鈦合金結構件具有相當大之誘因。
本研究所使用之基礎粉末為氣噴霧純鈦粉、細氫化鈦粉和粗氫化鈦粉，在添加之合金元素方面則為Nb、Ta、Mo、Si、Cu、Ni、Fe (CM羰基鐵粉)、Co和Sn等元素粉。研究結果顯示純鈦粉之延展性與雜質含量等性質皆優於氫化鈦粉，添加Nb、Ta、Mo、Cu和Sn合金元素可改善氫化鈦粉燒結工件之延展性，而在強度方面，添加Fe合金元素之氫化鈦粉或純鈦粉燒結工件皆具有最佳之強化效應。在1150℃持溫2小時條件下，使用鈦粉之純鈦與鈦合金燒結工件之密度皆可達到95%以上，且碳/氧含量分別低於0.10 與0.40 wt%。在快速冷卻製程下，Ti-7Fe之拉伸強度與伸長量分別為916 MPa和13%，此與退火後Ti-6Al-4V鑄鍛件之性質相近，若經740℃持溫24小時之熱處理，拉伸強度與伸長量則為976 MPa和12%，此Ti-7Fe之性質又與所用鐵粉有關。而在三元合金系統開發結果方面，Ti-7Fe-5Sn具有最佳之拉伸性質(1077 MPa和6%)。綜合上述實驗結果得知β相之體積分率、合金固溶量與α二次相析出等顯微組織將影響鈦合金之機械性質。
在TiC/Ti-7Fe鈦合金研究結果方面，OM與OS羰基鐵粉中的碳可快速均勻擴散至鈦基地中，形成微米級與奈米級TiC散佈強化之效應，此雙重效應為直接添加TiC所無法達到之效果。添加7 wt% OS羰基鐵粉製作TiC/Ti-7Fe鈦合金複合材之機械性質為1007 MPa的拉伸強度和10%的延性。

關鍵字

α＋β鈦合金 ； Ti-Fe合金 ； 冷卻速率 ； 熱處理

並列摘要

Powder metallurgy (PM) titanium alloys have been widely applied in the automobile, military, and biomedical industries due to its high specific strength, excellent corrosion and oxidation resistance, moderate strength at high temperatures, good biocompatibility, and low manufacturing cost.
This study examined the sintered properties of gas atomized pure titanium powder and titanium hydride powder. The gas atomized powder exhibited the best results. Also investigated are the effects of Nb, Ta, Mo, Si, Cu, Ni, Fe (CM carbonyl iron powder), Co, and Sn alloying powders on the mechanical properties and microstructures of α + β titanium alloys. The results indicated that all sintered alloys reached relative densities of 95% or higher, and the contents of carbon and oxygen were low at 0.10 and 0.40 wt%, respectively. The sintered Ti-7Fe using furnace cooling followed by fan cooling had a high tensile strength of 916 MPa, and the elongation was 13%. These properties are similar to those of the annealed wrought Ti-6Al-4V. With isothermal holding at 740 ℃ for 24 hours prior to fan cooling, the tensile strength further increased to 976 MPa, and the elongation was 12%. Moreover, Ti-7Fe-5Sn showed the best tensile properties in ternary systems with about 1077 MPa tensile strength and 6% elongation. The results suggest that large amounts of β phase with high iron content and fine precipitates within β phase will provide a good combination of strength, hardness, and elongation.
For TiC/Ti-7Fe alloys, the highest tensile strength (1007 MPa) and hardness (34 HRC) were produced by using pure titanium and OS carbonyl iron powders due to the presence of in situ formed TiC, and SiO2 particles in the as-received OS iron powder.

並列關鍵字

α + β Titanium Alloy ； Ti-Fe Alloy ； Cooling Rate ； Heat Treatment ； Titanium Matrix Composites

參考文獻

124. 吳筱涵，“製備鈦及鈦鎳合金之粉末冶金製程研究”，碩士論文，國立台灣大

Advanced Materials & Processes, 2001, Vol. 159, No. 10, pp. 43-46.

Technologies of Titanium Powder Metallurgy”, JOM: Journal of the Minerals,

Metals and Materials Society, 2004, Vol. 56, No. 11, pp. 46-48.

3. S. Lampman, “Wrought Titanium and Titanium Alloys”, Metals Hanndbook