Effect of Calcium on Structure, Phase Composition and Hardening of Al-Zn-Mg Alloys Containing up to 12wt.%Zn

Belov, Nikolay Aleksandrovich; Naumova, Evgenia Alexandrovna; Akopyan, Torgom Karoevich

doi:10.1590/1516-1439.036415

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Articles • Mater. Res. 18 (6) • Nov-Dec 2015 • https://doi.org/10.1590/1516-1439.036415 copy

Effect of Calcium on Structure, Phase Composition and Hardening of Al-Zn-Mg Alloys Containing up to 12wt.%Zn

Authorship SCIMAGO INSTITUTIONS RANKINGS

The influence of calcium on structure and phase composition of the aluminum alloys, containing additions of zinc up to 12 wt.% and magnesium (3.5 wt.%) was studied. The increase of Zn content leads to formation of Al₄Ca primary crystals at lower concentrations of calcium. Zinc is distributed between aluminum solid solution and intermetalic phases (Ca-containing and T- Al₂Mg₂Zn₃) in the alloys of the Al-Zn-Mg-Ca system. The eutectic (Al)+Al₄Ca has fine structure and particles of Al₄Ca are capable to spheroidization during heat treatment at 500 °С. The maximal level of hardness observed on calcium containing alloys was higher than 200 HB, what gives a reason to expect good strength properties. Due to summarized results it is seen that the Al-Zn-Mg-Ca system is promising for development of new eutectic type high-strength aluminum alloys.

Keywords:
high-strength aluminum alloys; phase composition; phase diagrams; thermodynamic calculations; castings; structure

No	Concentrations¹ 1 concentrations of impurities (particularly Fe and Si) are below 0.01 wt%. , wt%							No	Concentrations¹ 1 concentrations of impurities (particularly Fe and Si) are below 0.01 wt%. , wt%
	Zn	Ca		Mg		Al			Zn		Ca		Mg	Al
1	-	-		3.42		Balance		12	8.87		0.53		3.28	Balance
2	-	3.85		3.41		Balance		13	9.13		1.04		3.36	Balance
3	-	5.44		3.33		Balance		14	9.21		1.99		3.52	Balance
4	-	6.54		3.35		Balance		15	9.12		2.87		3.63	Balance
5	-	7.25		3.44		Balance		16	8.84		3.85		3.55	Balance
6	5.88	-		3.54		Balance		17	8.95		4.55		3.47	Balance
7	6.25	1.04		3.46		Balance		18	11.07		2.94		3.51	Balance
8	6.14	1.87		3.32		Balance		19	11.74		-		3.45	Balance
9	5.89	2.97		3.46		Balance		20	12.45		1.85		3.47	Balance
10	5.93	-		3.64		Balance		21	11.73		2.28		3.34	Balance
11	5.98	0.25		3.39		Balance		22	12.34		4.05		3.64	Balance
Reference alloy 7055
	Zn		Mg		Cu		Zr			Fe		Si		Al
	7.95		2.08		2.44		0.12			0.08		0.05		Balance

Number of spector	Concentrations, wt%				Phase identification
Number of spector	Mg	Al	Ca	Zn	Phase identification
1	0.38	42.91	20.74	35.97	Primary Al₄Ca
2	0.57	42.74	20.91	35.78	Primary Al₄Ca
3	0.94	43.58	19.69	35.79	Primary Al₄Ca
4	0.25	43.8	17.8	37.29	Primary Al₄Ca
5	11.91	26.58	0.03	61.48	Al₂Mg₃Zn₃ eutectic
6	8.96	29.83	1.11	59.96	Al₂Mg₃Zn₃ eutectic
7	6.99	34.43	1.02	56.9	Al₂Mg₃Zn₃ eutectic
8	6.76	43.37	1.73	48.08	Al₂Mg₃Zn₃ eutectic
9	0.68	78.13	3.49	17.54	Eutectic
10	1.08	75.86	3.39	19.64	Eutectic
11	0.8	75.33	3.98	19.73	Eutectic
12	4.74	90.34	0.09	4.66	(Al)
13	1.86	94	0.23	3.73	(Al)
14	2.09	93.98	0	3.91	(Al)
15	1.35	94.89	0.08	3.54	(Al)
16	2.15	80.58	6.61	10.51	Eutectic
17	2.29	78.47	7.17	11.94	Eutectic
18	2.13	79.14	6.99	11.61	Eutectic
19	4.7	76.76	5.73	12.72	Eutectic

	Al	Zn	Mg	Ca
Precipitates
T¹ 1 Т: Al2Mg3Zn3; М: MgZn2.	+	+	+	–
M¹ 1 Т: Al2Mg3Zn3; М: MgZn2.	+–² 2 “+” and “–” symbols indicate the presence or absence of elements in the phases.	+	+	–
Eutectic and primary phases
T¹ 1 Т: Al2Mg3Zn3; М: MgZn2.	+	+	+	–
M¹ 1 Т: Al2Mg3Zn3; М: MgZn2.	+–	+	+	–
Al₂CaZn₂	+	+	–	+
Al₄Ca	+	+	–	+
CaZn₁₃	–	+	–	+

No	Content, wt.%		HB
No	Zn	Ca	Q	T4	T6
1	0	0	57 ± 2	58 ± 1	57 ± 2
2	0	4	82 ± 2	84 ± 3	84 ± 2
3	6	0	87 ± 3	119 ± 2	179 ± 1
4	6	1	98 ± 3	119 ± 2	167 ± 4
5	6	2	95 ± 4	114 ± 4	172 ± 3
6	6	4	98 ± 3	103 ± 3	104 ± 5
7	12	0	124 ± 2	157 ± 5	201 ± 4
8	12	2	138 ± 4	165 ± 5	211 ± 4
9	12	3	139 ± 5	164 ± 4	219 ± 5
10	12	4	138 ± 5	159 ± 4	215 ± 5

ABM, ABC, ABPol UFSCar - Dep. de Engenharia de Materiais, Rod. Washington Luiz, km 235, 13565-905 - São Carlos - SP- Brasil. Tel (55 16) 3351-9487 - São Carlos - SP - Brazil
E-mail: pessan@ufscar.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *e-mail: nemiroffandtor@yandex.ru